Samacheer Kalvi Class 5 Science Solutions Term 1 Chapter 3 Energy

Evaluation

I. Choose the Correct Answer:

 

Question 1. When diesel is burnt chemical energy is converted into _____.
(a) wind energy
(b) heat energy
(c) solar energy
(d) sound energy
Answer: (b) heat energy
In simple words: When diesel burns, the stored chemical energy changes into heat energy. This heat can then be used to do work, like moving a vehicle.

🎯 Exam Tip: Remember that burning fuels always converts chemical energy into heat energy, often accompanied by light energy.

 

Question 2. Running water possesses _____.
(a) potential energy
(b) chemical energy
(c) kinetic energy
(d) sound energy
Answer: (c) kinetic energy
In simple words: Any object that is moving has kinetic energy. Since running water is moving, it has kinetic energy.

🎯 Exam Tip: Kinetic energy is the energy of motion, while potential energy is stored energy due to position or state.

 

Question 3. Unit of energy is _____.
(a) Kilogram
(b) Newton
(c) Kelvin
(d) Joule
Answer: (d) Joule
In simple words: The standard unit used to measure energy is called a Joule. This unit helps scientists and engineers compare different amounts of energy.

🎯 Exam Tip: Knowing the standard units for common physical quantities like energy, mass, and force is important for calculations.

 

Question 4. Which one of the following requires wind energy?
(a) Bicycle
(b) Photosynthesis
(c) Parachute
(d) Automobiles
Answer: (c) Parachute
In simple words: A parachute needs the force of wind to slow down its fall. The wind pushes against the parachute, creating drag.

🎯 Exam Tip: Think about how each item functions and what kind of force or energy it primarily interacts with to perform its purpose.

 

Question 5. Cow dung possesses _____.
(a) kinetic energy
(b) chemical energy
(c) solar energy
(d) heat energy
Answer: (b) chemical energy
In simple words: Cow dung stores energy in its chemical bonds, which can be released as heat or biogas when it decomposes or is burned. This is similar to how wood or other fuels store energy.

🎯 Exam Tip: Remember that substances like fuels, food, and animal waste store energy in their chemical structure.

II. Find Out the Energy Conversion That Takes Place in the Following:

 

Question 1. Iron box:
Answer: Chemical energy to Heat energy
In simple words: The iron box converts stored chemical energy into heat. This heat is then used to iron clothes.

🎯 Exam Tip: Always identify the initial energy form and the final useful energy form in any conversion process.

 

Question 2. Electric Iron box:
Answer: Electric energy to Heat energy
In simple words: An electric iron changes electricity into heat. This heat helps to make clothes smooth.

🎯 Exam Tip: Most electrical heating devices work by converting electrical energy directly into thermal (heat) energy.

 

Question 3. Electric fan:
Answer: Electric energy to Mechanical energy
In simple words: An electric fan uses electricity to make its blades spin. The spinning blades create wind, which is a form of mechanical energy.

🎯 Exam Tip: Appliances that cause movement, like fans, washing machines, or mixers, convert electrical energy into mechanical energy.

 

Question 4. Speaker:
Answer: Electric energy to Sound energy
In simple words: A speaker takes in electrical signals and turns them into sound waves that we can hear. This process involves a small motor that vibrates.

🎯 Exam Tip: For devices like speakers, radios, or telephones, the primary energy conversion involves transforming electrical signals into sound.

 

Question 5. Generator:
Answer: Mechanical energy to Electrical energy
In simple words: A generator works by using movement (mechanical energy) to create electricity. It's the opposite of an electric motor.

🎯 Exam Tip: Generators are essential for power production, converting mechanical power (from turbines, engines) into electrical power.

III. Find Out Form of Energy Possessed by the Following Things:

 

Question 1. A rock on the top of a hill.
Answer: Potential Energy
In simple words: A rock high up on a hill has stored energy because of its position. This stored energy is called potential energy.

🎯 Exam Tip: Objects held at a height, stretched springs, or compressed gas all possess potential energy.

 

Question 2. A rolling ball.
Answer: Kinetic Energy
In simple words: A ball that is rolling is in motion, so it has energy of movement. This energy is called kinetic energy.

🎯 Exam Tip: Anything that is moving, from a car to a running child, possesses kinetic energy.

 

Question 3. Charcoal.
Answer: Heat Energy
In simple words: Charcoal stores chemical energy that can be released as heat when burned. This heat is what makes it useful for cooking.

🎯 Exam Tip: Fuels like charcoal, wood, and coal store chemical energy that is converted into heat upon combustion.

 

Question 4. (Implied: A moving object.)
Answer: Kinetic Energy
In simple words: Any object that is in motion has kinetic energy. The faster it moves, the more kinetic energy it has.

🎯 Exam Tip: Kinetic energy is directly related to an object's mass and its speed, meaning heavier or faster objects have more kinetic energy.

 

Question 5. Battery.
Answer: Chemical Energy
In simple words: A battery stores energy in the form of chemicals. When connected, these chemicals react and produce electrical energy.

🎯 Exam Tip: Batteries are a common example of how chemical energy can be converted into electrical energy on demand.

IV. Match the Following:

 

Question 1. Match the following:

Answer:
1. e (Electric bell - Sound energy)
2. d (Water in dam - Potential energy)
3. a (Solar heater - Solar energy)
4. c (Wind mill - Electrical energy)
5. b (Torch light - Light energy)
In simple words: The answer matches each item with its main type of energy or the energy it uses or produces. For example, an electric bell makes sound, and water in a dam stores energy because of its height.

🎯 Exam Tip: When matching, clearly understand the primary function or stored energy of each item to pair it correctly.

V. Say True or False:

 

Question 1. An apple falling from a tree is an example for kinetic energy.
Answer: True
In simple words: As the apple falls, it is moving, so it has energy of motion, which is kinetic energy. Before it falls, while hanging on the tree, it has potential energy.

🎯 Exam Tip: Remember that falling objects convert their stored potential energy into kinetic energy as they move downwards.

 

Question 2. Electrical energy is used to run electric trains.
Answer: True
In simple words: Electric trains use electricity from overhead lines or tracks to power their motors and move. This is a common way to travel in many places.

🎯 Exam Tip: Think about common modes of transport and their energy sources; electric trains are a clear example of electrical energy in action.

 

Question 3. Heat energy cannot be produced by friction.
Answer: False
In simple words: Heat energy can definitely be produced by friction. When two surfaces rub against each other, they create heat, like rubbing your hands together to warm them up.

🎯 Exam Tip: Friction is a force that opposes motion and always generates heat, which is why mechanical systems often need cooling.

 

Question 4. Potential energy and heat energy are the two forms of mechanical energy.
Answer: False
In simple words: Mechanical energy includes potential energy and kinetic energy, but not heat energy. Heat energy is a different form of energy.

🎯 Exam Tip: Distinguish between mechanical energy (potential + kinetic) and other forms like thermal (heat), chemical, or electrical energy.

 

Question 5. The unit of energy is joule.
Answer: True
In simple words: The joule is the standard unit for measuring energy, meaning how much work can be done or how much heat is transferred.

🎯 Exam Tip: Always remember that the Joule is the standard (SI) unit for both energy and work.

VI. Answer in Brief:

 

Question 1. What is energy?
Answer: Energy is the ability to do work. It allows things to move, heat up, or change form. The S.I unit of work is Joule.
In simple words: Energy is simply the power to make things happen, like moving something or making it hot.

🎯 Exam Tip: A concise definition of energy is "the capacity to do work," which covers all its forms and manifestations.

 

Question 2. What are the different forms of energy?
Answer: There are many different forms of energy. These include mechanical energy, heat energy, light energy, wind energy, solar energy, electrical energy, and chemical energy.
In simple words: Energy comes in different types, like the energy of motion, heat, light, wind, sun, electricity, and stored energy in things like food.

🎯 Exam Tip: Be ready to list and briefly describe several forms of energy, as understanding their distinctions is fundamental.

 

Question 3. What are the uses of mechanical energy?
Answer: Mechanical energy has several uses:

• In hydroelectric plants, the kinetic energy of moving water is turned into electrical energy.
• Windmills use the kinetic energy of wind to make electrical energy.
• Mechanical energy from a hammer is used to push a nail into something.
• Mechanical energy can stop a moving object or make a still object move.

Water flowing through a dam is a perfect example of mechanical energy at work.
In simple words: Mechanical energy helps us in many ways, like making electricity from water or wind, hammering nails, and making things move or stop.

🎯 Exam Tip: When explaining uses, try to give practical, everyday examples where mechanical energy is clearly at play, focusing on its ability to cause movement or apply force.

 

Question 4. State the Law of conservation of energy.
Answer: The Law of Conservation of Energy states that energy can never be created or destroyed. Instead, it only changes from one form to another. For example, a rolling ball changes potential energy to kinetic energy.
In simple words: Energy cannot be made or unmade, it just changes from one type to another, like a ball rolling down a hill.

🎯 Exam Tip: This law is a cornerstone of physics; make sure to mention both that energy cannot be created or destroyed, and that it only changes form.

 

Question 5. Give the uses of Light energy.
Answer: Light energy has several important uses:

• We use light energy to see objects around us.
• Plants use light energy from the sun to make their own food through photosynthesis.
• Our skin uses light energy to create Vitamin D, which is good for our bones.
• Electricity can be produced using light energy, especially from the sun, through solar panels.

Sunlight is a natural and renewable source of light energy.
In simple words: Light energy helps us see, helps plants make food, helps our bodies make Vitamin D, and can even be used to make electricity.

🎯 Exam Tip: When discussing light energy, always include its role in vision and photosynthesis, as these are primary biological functions.

VII. Answer in Detail:

 

Question 1. Explain the types of Mechanical energy.
Answer: Mechanical energy is the energy an object has because of its movement or its position. It can be divided into two main types:

• Kinetic energy: This is the energy an object has due to its motion. It is also known as energy of motion. For example, a moving car, a cricket ball thrown by a player, or a bullet shot from a gun all have kinetic energy.
• Potential energy: This is the stored energy an object has because of its position or state. It is also known as energy of position. For instance, an object lifted high up, a stone in a stretched rubber band, or water held in a dam all have potential energy.

Both kinetic and potential energy are fundamental to understanding how machines and natural systems work.
In simple words: Mechanical energy is about how things move or where they are placed. It has two types: kinetic energy (for moving things like a car) and potential energy (for stored energy like a rock on a hill).

🎯 Exam Tip: Clearly define mechanical energy first, then describe kinetic and potential energy separately, providing clear examples for each.

 

Question 2. Explain Conservation of energy.
Answer: Energy cannot be created or destroyed. It simply changes from one form to another or moves from one object to another. Here are some daily life examples of how energy is conserved:
1. Water dam:

• When water falls from a height in a dam, its potential energy (stored energy due to height) changes into kinetic energy (energy of motion).
• This moving water then rotates turbines, and this mechanical energy is used to generate electrical energy.

2. Electrical appliances:

• Electrical energy powers many household items like electric stoves, iron boxes, and fans.
• Electricity flows into a heating coil inside these devices.
• As current passes through, the coil gets hot.
• This heat energy helps us perform various tasks. For instance, an iron box uses heat to smooth clothes, while a fan converts electrical energy into mechanical energy to move air. A computer converts electrical energy to light and sound energy.

3. Driving a car:

• Cars use fuels like petrol, diesel, or gas.
• When this fuel burns in the engine, its chemical energy changes into heat energy.
• This heat creates hot gases that push the engine's pistons, causing the vehicle to move.
• So, heat energy is converted into mechanical energy, which drives the car.

In all these examples, the total amount of energy remains constant; it just changes its form.
In simple words: Energy never disappears; it just switches forms. For example, water falling in a dam makes electricity, fuel burning in a car makes it move, and electricity heats up an iron box.

🎯 Exam Tip: Illustrate the law of conservation of energy with specific, well-explained examples from daily life to demonstrate your understanding of energy transformations.

Samacheer Kalvi 5th Science Guide Energy Additional Questions and Answers

I. Choose the Correct Answer

 

Question 1. _____ is the only form of energy visible to human eye.
(a) Heat energy
(b) Light energy
(c) Electrical energy
(d) Chemical energy
Answer: (b) Light energy
In simple words: Out of all the different kinds of energy, only light energy can be seen by people. This is how we see everything around us.

🎯 Exam Tip: Consider which type of energy interacts directly with our eyes to enable vision; light is the only one.

 

Question 2. Light travels at a speed of _____.
(a) 3,00,000 km/s
(b) 4,00,000 km/s
(c) 5,00,000 km/s
(d) 6,00,000 km/s
Answer: (a) 3,00,000 km/s
In simple words: Light moves incredibly fast, traveling about 300,000 kilometers every second. This speed is constant in a vacuum.

🎯 Exam Tip: The speed of light is a fundamental constant in physics, important to remember for various scientific contexts.

 

Question 3. Sunlight takes _____ to reach earth.
(a) 5 minutes
(b) 6 minutes
(c) 7 minutes
(d) 8 minutes
Answer: (a) 5 minutes
In simple words: It takes sunlight around 5 minutes to travel from the sun all the way to Earth. This shows how far away the sun is.

🎯 Exam Tip: Knowing the approximate travel time of sunlight is a good indicator of the vast distances in our solar system.

 

Question 4. Which of the following device converts chemical energy into electrical energy?
(a) Battery
(b) Loud speaker
(c) Solar cell
(d) Electrical motor
Answer: (a) Battery
In simple words: A battery uses chemical reactions inside it to create electrical energy. This is why we use batteries to power many devices.

🎯 Exam Tip: Understand the primary energy conversion for common devices; batteries are a classic example of chemical to electrical energy.

 

Question 5. _____ stands first in generating electricity from wind mill.
(a) Kerala
(b) Tamil Nadu
(c) Karnataka
(d) Andhra pradesh
Answer: (b) Tamil Nadu
In simple words: Tamil Nadu is known for being a leader in producing electricity from wind power using many windmills. It has strong winds suitable for this.

🎯 Exam Tip: Geographical knowledge regarding renewable energy sources, like wind power, can be asked in general knowledge or environmental science questions.

 

Question 6. The energy, possessed by an object due to its position is called _____.
(a) Kinetic energy
(b) Potential energy
(c) Mechanical energy
(d) Electrical energy
Answer: (b) Potential energy
In simple words: When an object is held high up or stretched, it stores energy because of its state or position. This stored energy is called potential energy.

🎯 Exam Tip: Potential energy is "stored energy," often related to an object's height (gravitational potential) or its elastic state (elastic potential).

 

Question 7. The energy possessed by a cricket ball bowled by a player is _____.
(a) Potential energy
(b) Kinetic energy
(c) Light energy
(d) Electrical energy.
Answer: (b) Kinetic energy
In simple words: A cricket ball that is bowled is moving fast, so it has kinetic energy, which is the energy of motion. Kinetic energy is a type of mechanical energy.

🎯 Exam Tip: For any moving object, remember that its primary energy type is kinetic energy, as it is actively in motion.

 

Question 8. Electric eel is a _____.
(a) fish
(b) snake
(c) frog
(d) none of the options
Answer: (a) fish
In simple words: An electric eel is a type of fish that can create strong electric shocks to protect itself or catch prey.

🎯 Exam Tip: Knowledge about unique animal adaptations, like the electric eel's ability to generate electricity, is often tested.

 

Question 9. Which of the following is the example potential energy?
(a) Object lifted above
(b) Bullet coming out of a gun
(c) Moving car
(d) Cricket ball bowled by a player
Answer: (a) Object lifted above
In simple words: An object that has been lifted up has stored energy because of its height. This stored energy is called potential energy. Other options involve motion, which is kinetic energy.

🎯 Exam Tip: Carefully distinguish between situations involving height or position (potential energy) and those involving movement (kinetic energy).

 

Question 10. What energy is possessed by stretched rubber.
(a) Nuclear
(b) Potential
(c) Kinetic
(d) Thermal
Answer: (b) Potential
In simple words: When rubber is stretched, it stores energy. This stored energy, which can be released when the rubber snaps back, is called potential energy.

🎯 Exam Tip: A stretched or compressed spring, a stretched rubber band, or a wound-up toy all store elastic potential energy.

II. Fill in the Blanks:

 

Question 1. _____ is a measure of heat in a body.
Answer: Temperature
In simple words: Temperature tells us how hot or cold something is, which is a way to measure the amount of heat energy present.

🎯 Exam Tip: Temperature is the degree of hotness or coldness, while heat is the transfer of thermal energy.

 

Question 2. _____ use wind energy to generate electricity.
Answer: Windmills
In simple words: Windmills have large blades that turn when the wind blows, and this movement is used to create electricity.

🎯 Exam Tip: Windmills (or wind turbines) are a key technology for converting the kinetic energy of wind into electrical energy.

 

Question 3. The form of energy that produces feeling of hotness is called as _____.
Answer: heat
In simple words: When we feel hot, it is because of heat energy, also known as thermal energy.

🎯 Exam Tip: Heat is the form of energy associated with the sensation of warmth and the movement of atoms and molecules.

 

Question 4. Light energy helps our skin to synthesis _____.
Answer: Vitamin D
In simple words: When our skin is exposed to sunlight, it uses the light energy to produce Vitamin D, which is good for our health.

🎯 Exam Tip: Remember that Vitamin D synthesis in the skin is a crucial biological process facilitated by sunlight exposure.

 

Question 5. When stored water falls down, potential energy of water is converted into _____.
Answer: Kinetic energy
In simple words: As water stored at a height (like in a dam) falls, its stored energy turns into energy of motion. This moving water can then be used to generate power.

🎯 Exam Tip: This is a classic example of energy transformation: potential energy (due to height) becomes kinetic energy (due to motion).

 

Question 6. Electric eel can generate _____.
Answer: electricity
In simple words: Electric eels are amazing creatures that can produce their own electricity to defend themselves or stun prey.

🎯 Exam Tip: This question highlights how some biological systems can generate and utilize electrical energy.

 

Question 7. Law of conversation of energy given by _____.
Answer: Julius Robert Mayer
In simple words: The idea that energy can only change forms and not be created or destroyed was first suggested by a scientist named Julius Robert Mayer.

🎯 Exam Tip: It is good to know the scientists associated with fundamental laws, as it adds depth to your understanding of scientific history.

III. Say True or False:

 

Question 1. Light does not require any medium to travel.
Answer: True
In simple words: Light is special because it can travel through empty space, like between the sun and Earth, without needing air or water to carry it.

🎯 Exam Tip: This property makes light different from sound, which requires a medium (like air or water) to travel.

 

Question 2. Mechanical energy can be used for pumping water.
Answer: True
In simple words: Mechanical energy, such as the effort from turning a hand pump or the rotation of a motor, can be used to lift and move water.

🎯 Exam Tip: Mechanical energy is versatile and directly applicable to tasks involving force, motion, and work, such as pumping fluids.

 

Question 3. Heat energy is used to run vehicles.
Answer: True
In simple words: Many vehicles, like cars and trains, use heat energy from burning fuel to power their engines and make them move.

🎯 Exam Tip: Internal combustion engines in most vehicles convert chemical energy in fuel into heat, which then drives mechanical motion.

 

Question 4. Heat is measured in Joule.
Answer: True
In simple words: Just like other forms of energy, heat energy is also measured using the unit called a Joule.

🎯 Exam Tip: The Joule is the standard unit for all forms of energy, including heat, work, and electrical energy.

 

Question 5. A book lying on a table possesses kinetic energy.
Answer: False
In simple words: A book lying still on a table does not have kinetic energy because it is not moving. It possesses potential energy due to its height from the ground.

🎯 Exam Tip: Kinetic energy is strictly associated with motion; an object at rest only has potential energy relative to a reference point.

IV. Circle the Odd One:

 

Question 1.
(a) Proton
(b) Dentron
(c) Electron
(d) Neutron
Answer: (b) Dentron
In simple words: Among the given options, Dentron is the odd one out because protons, electrons, and neutrons are common subatomic particles, while 'Dentron' is not a standard particle name. Protons, electrons, and neutrons are the main particles that make up atoms.

🎯 Exam Tip: When asked to identify the odd one out, look for a category or common characteristic that most items share, and find the one that doesn't fit.

 

Question 2.
(a) Nuclear power plants
(b) Hydroelectric plants
(c) Water heaters
(d) Windmills
Answer: (c) Water heaters
In simple words: Nuclear power plants, hydroelectric plants, and windmills all generate electricity, but water heaters use electricity or other energy to heat water; they do not generate electricity. These power plants use different methods, like splitting atoms or using moving water and wind, to produce electricity for our homes and industries.

🎯 Exam Tip: For "odd one out" questions, quickly consider the primary function or category of each item to spot the outlier.

V. Match the Following:

 

Question 1. Match the following:
1. Light energy
2. Potential energy
3. Heat energy
4. Electric eel
(a) Water dams
(b) Thermal energy
(c) Electric energy
(d) 3,00,000 km/s
Answer:
1. d (Light energy - 3,00,000 km/s, which is the speed of light)
2. a (Potential energy - Water dams, as water stored in a dam has potential energy)
3. b (Heat energy - Thermal energy, as they are synonyms)
4. c (Electric eel - Electric energy, as electric eels produce electric energy)
In simple words: We connect each item on the left to its correct pair on the right based on its main characteristic or related concept. For example, light energy is linked to its speed, and water in a dam is known for potential energy.

🎯 Exam Tip: Read both columns carefully and identify keywords or concepts to find the most appropriate match. Sometimes one match can help you deduce others.

 

Question 2. Match the following appliances with the type of energy they primarily produce or use:
1. Iron box
2. Laptop
3. Bulb
4. Fan
(a) Mechanical Energy
(b) Light Energy
(c) Light and Sound Energy
(d) Heat Energy
Answer:
1. d (Iron box produces Heat Energy)
2. c (Laptop produces Light and Sound Energy)
3. b (Bulb produces Light Energy)
4. a (Fan produces Mechanical Energy)
In simple words: We match each electrical appliance to the main type of energy it gives out or uses for its primary function. For example, an iron gets hot, so it matches heat energy.

🎯 Exam Tip: Think about the main purpose of each appliance. For example, a fan's main purpose is to move air, which is a form of mechanical energy.

VI. Answer Briefly:

 

Question 1. What is mechanical energy?
Answer: Mechanical energy is the energy an object has because of its movement or its position. It can be divided into two main types: kinetic energy, which is the energy of motion, and potential energy, which is stored energy due to position. For example, a rolling ball has kinetic energy, while water held behind a dam has potential energy.
In simple words: Mechanical energy is the power an object has from moving or from where it is placed. It includes moving energy (kinetic) and stored energy (potential).

🎯 Exam Tip: When defining a term like mechanical energy, always include its two main forms (kinetic and potential energy) and a simple example for clarity.

 

Question 2. What is energy of motion? Give examples.
Answer: Energy of motion is also called kinetic energy. It is the energy that a moving object has. For instance, a car moving, a cricket ball thrown by a player, or a bullet shot from a gun all have kinetic energy because they are in motion. The faster an object moves and the heavier it is, the more kinetic energy it has.
In simple words: Energy of motion is the power something has when it is moving. Examples are a moving car or a thrown ball.

🎯 Exam Tip: When asked for examples, choose clear, relatable scenarios that truly demonstrate the concept of motion creating energy.

 

Question 3. Write any two uses of mechanical energy.
Answer: Mechanical energy is used in several ways. For example, windmills use the moving air's mechanical energy to make electricity. Also, when a hammer hits a nail, it uses mechanical energy to push the nail into a surface. Many machines, from simple levers to complex engines, rely on mechanical energy to perform work.
In simple words: Windmills use moving air's mechanical energy to make power. A hammer uses mechanical energy to push a nail.

🎯 Exam Tip: Provide diverse examples of mechanical energy applications, such as a large-scale power generation and a simple tool, to show a broad understanding.

 

Question 4. What is wind energy and write its uses?
Answer: Wind energy is the energy that moving air (wind) possesses. It has many uses:
- Windmills capture wind energy to create electricity.
- Ships use the wind's power in their sails to move across water.
- Fun sports like windsurfing, sailing, and kitesurfing all depend on wind energy.
- Wind energy can also be used to pump water from wells or for irrigation.
Wind is a clean and renewable source of energy, making it important for sustainable power generation.
In simple words: Wind energy is power from moving air. It helps make electricity, sail boats, power sports, and pump water.

🎯 Exam Tip: When describing wind energy, remember to list both its definition and its various practical applications, highlighting its role in daily life and power generation.

 

Question 5. Name the particles of atom?
Answer: Atoms are made up of three basic particles: protons, electrons, and neutrons. Protons and neutrons are found in the center (nucleus), while electrons move around it. These tiny particles determine the properties and behavior of every element in the universe.
In simple words: The tiny parts that make up an atom are protons, electrons, and neutrons.

🎯 Exam Tip: Always list all three fundamental subatomic particles (protons, neutrons, electrons) when asked about the composition of an atom.

 

Question 6. What is electric energy?
Answer: Electric energy is the energy that comes from the movement of electrons within objects. This flow of electrons creates an electric current, which can power devices. It is a versatile form of energy that can be easily converted into other forms like light, heat, or mechanical energy.
In simple words: Electric energy is the power caused by electrons moving in things. This energy makes electric devices work.

🎯 Exam Tip: When explaining electric energy, emphasize the role of electron movement and its practical applications in powering devices.

 

Question 7. What are the different ways electricity can be generated?
Answer: Electricity can be generated in many ways. It is produced in nuclear power plants, which use atomic energy. Hydroelectric plants generate electricity from moving water, and windmills use wind. Solar energy also generates electricity using sunlight. Each method has its own benefits and challenges, contributing to a diverse energy supply.
In simple words: Electricity can be made using nuclear power, moving water (hydroelectric), wind (windmills), and sunlight (solar energy).

🎯 Exam Tip: List a variety of generation methods to show a comprehensive understanding, distinguishing between fossil fuels, renewables, and nuclear power.

 

Question 8. Write the uses of Electric energy.
Answer: Electric energy is used in many parts of our daily lives. It powers common home appliances like fans, lights, televisions, washing machines, and refrigerators. Electrical energy also makes electric irons, stoves, and water heaters work. It is also essential for transportation, running cars and trains, and is used in factories to manufacture different products. Modern society relies heavily on electricity for almost all aspects of daily living, from communication to healthcare.
In simple words: Electric energy powers home appliances like fans and TVs. It also runs cars, trains, and helps in factories to make things.

🎯 Exam Tip: Provide a wide range of examples, from everyday household items to transportation and industrial applications, to illustrate the extensive uses of electric energy.

 

Question 9. What is law of conservation of energy?
Answer: The law of conservation of energy states that energy cannot be created from nothing, nor can it be completely destroyed. Instead, energy can only change from one form to another, or move from one object to another. This important law was discovered by Julius Robert Mayer. This fundamental principle helps us understand how energy works in everything from a simple light bulb to the complex processes within stars.
In simple words: The law of conservation of energy says that energy can only change its form or move. It cannot be made or destroyed.

🎯 Exam Tip: Remember to mention both aspects of the law: energy cannot be created or destroyed, only transformed or transferred. Naming the scientist (Julius Robert Mayer) adds detail.

 

Question 10. What energy transfer happen in a car engine?
Answer: In a car engine, when fuel like petrol, diesel, or gas burns, the chemical energy stored in the fuel changes into heat energy. This heat creates hot gases that push the engine's pistons. The movement of these pistons then converts the heat energy into mechanical energy, which makes the vehicle move. This process of converting chemical energy to heat and then to mechanical work is what allows cars to drive.
In simple words: In a car engine, chemical energy from fuel turns into heat. This heat then makes the engine parts move, which is mechanical energy, to power the car.

🎯 Exam Tip: Clearly state the sequence of energy transformations: chemical to heat, then heat to mechanical energy, to fully explain the process in a car engine.

VII. Answer in Detail:

 

Question 1. Write the uses of heat energy and light energy.
Answer:
Uses of Heat Energy:
Heat energy is very useful in many ways. It is used in power stations to generate electricity. Fuels like petrol and diesel provide heat energy to power vehicles. We use heat to cook food, which makes it soft and easier to digest. Heat is also used to shape hard materials like iron and to dry clothes and other wet items.

Uses of Light Energy:
Light energy allows us to see objects around us. Plants use light energy from the sun to create their own food through a process called photosynthesis. Our skin also uses light energy to make Vitamin D, which is good for our bones. Additionally, electricity can be generated using light energy, such as with solar panels. Both heat and light energy are forms of electromagnetic radiation, playing vital roles in our environment and technology.
In simple words: Heat energy helps us cook, dry clothes, shape metals, run vehicles, and make electricity. Light energy helps us see, helps plants grow food, helps our skin make Vitamin D, and can also make electricity.

🎯 Exam Tip: For "uses" questions, organize your answer into clear categories (e.g., "Uses of Heat Energy" and "Uses of Light Energy") and provide multiple distinct examples for each.

 

Question 2. Explain about chemical energy and its uses.
Answer: Chemical energy is the energy stored within the bonds of chemical compounds. This energy is released when atoms rearrange during chemical reactions.
Uses of Chemical Energy:
- The food we eat holds chemical energy, which our bodies use for growth and activity.
- Wood contains chemical energy that releases heat when burned, which we use for cooking.
- Coal also has chemical energy, which is burned in power plants to produce electricity.
- Batteries store chemical energy, which they convert into electrical energy to power devices.
- Fuels such as petrol and diesel contain chemical energy that powers vehicles when burned.
Chemical energy is essential for life processes and is a major source of energy for human activities.
In simple words: Chemical energy is stored in things like food, wood, coal, and fuels. It gives us power to move, cook, make electricity, and run vehicles.

🎯 Exam Tip: When defining chemical energy, highlight that it's stored in bonds and released in reactions. For uses, focus on examples from nature and technology.

 

Question 3. Draw the diagram to show how the electric energy generated from water.
Answer: The diagram below shows how hydroelectric power plants generate electricity using water.

In simple words: Water stored behind a dam falls, turning a turbine. The turbine then spins a generator to make electricity. This electricity is sent through transformers and power lines to homes and cities.

🎯 Exam Tip: When drawing diagrams for energy generation, clearly label each key component and show the direction of energy flow with arrows.