Multiple Choice Questions
Question. Magnetic effect of current was discovered by
Question. Inside the magnet, the field lines moves
(a) from north to south
(b) from south the north
(c) away from south pole
(d) away from north pole
Question. Relative strength of magnetic field at a point in the space surrounding the magnet is shown by the
(a) length of magnet
(b) thickness of magnet
(c) degree of closeness of the field.
(d) resistance offered by the surroundings
Question. Which of the following statement is not correct about the magnetic field?
(a) Magnetic field lines form a continuous closed curve.
(b) Magnetic field line do not interest each other.
(c) Direction of tangent at any point on the magnetic field line curve gives the direction of magnetic field at that point.
(d) Outside the magnet, magnetic field lines go from South to North pole of the magnet.
Question. By which instrument, the presence of magnetic field be determined?
(a) Magnetic Needle
Question. The pattern of the magnetic field produced by the straight current carrying conducting wire is
(a) in the direction opposite to the current
(b) in the direction parallel to the wire
(c) circular around the wire
(d) in the same direction of current
Question. The strength of magnetic field around a current carrying conductor is
(a) inversely proportional to the current but directly proportional to the square of the distance from wire.
(b) directly proportional to the current and inversely proportional to the distance from wire.
(c) directly proportional to the distance and inversely proportional to the current
(d) directly proportional to the current but inversely proportional the square of the distance from wire.
Question. A current through a horizontal power line flows from south to North direction. The direction of magnetic field line 0.5m above it is
Question. The nature of magnetic field line passing through the centre of current carrying circular loop is
(d) straight line
Question. The strength of each of magnet reduces to half when it cut along its length into the equal parts magnetic field strength of a solenoid. Polarity of solenoid can be determined by
(a) use of compass needle
(b) Right hand thumb rule
(c) Fleming left hand rule
(d) either (a) or (b)
Question. The factors on which one magnetic field strength produced by current carrying solenoids depends are
(a) Magnitude of current
(b) Number of turns
(c) Nature of core material
(d) All of the above
Question. A soft iron bar is introduced inside the current carrying solenoid. The magnetic field inside the solenoid
(a) will decrease
(b) will remains sam
(c) will increase
(d) will become zero
Question. Which one of the following is a temporary magnet
(a) Bar magnet
(b) Horse shoe magnet
(d) None of these
Question. What is the direction of magnetic field lines inside a solenoid?
(a) North to north
(b) South to north
(c) North to south
(d) East to south
Question. The size of concentric circles of magnetic field lines increases with distance from the conductor
(a) which shows that magnetic field decreases with distance.
(b) which shows that magnetic field increases with distance.
(c) which shows that magnetic field decreases with direction.
(d) which shows that magnetic field increase s with direction.
Question. MrNarasimhan a 65 year old person often complained of neck pain. One day his grandson Avinash, suggested that magnetic therapy is very effective in reducing such pains. He said that the permanent magnet/electromagnet, used in the device will help to produce Joule’s heating effects in the blood stream, which helps the blood flow better. He immediately contacted his friend in Chennai, who was running Magnetic Therapy Clinic. Mr. Narasimhan felt better.
a. What two values did Avinash exhibit towards his grandfather? Mention any two
Answer: Responsible behavior, concern and awareness
b. What is the SI unit of magnetic induction and define it?
Answer: Tesla (defn)
Question. Ms Nita chander found that her son could not hear properly. Mother took her to the specialist who prescribed hearing aid for her son. Hearing aids consist of electromagnets in the loudspeakers used in the device.
a. What two values does Ms Nita exhibit towards her son and students? Mention any two (caring attitude, sensitive towards society, concern for others
c. What is an electromagnet? In what way its hysteresis curve is different from that used for permanent magnets?
nswer: Electromagnet- temporary magnet.Hysteresis curve has small area, small coercivity, small retentivity.
Question. MsSumathy wife of Mr.Varadan complained about the non availability of gas cylinders and explained to him to look out for alternate methods for cooking. Mr.Varadan bought an induction stove to overcome the fuel problem. The next day Sumathy used her copper bottom cooker and kept it on the induction stove. But even after using it for half an hour she found that the cooker was not hot and food not cooked. As she was not aware of themethod to use the induction stove, she asked her elder daughter Dhanya, studying first year engineering about it. She told her, that some vessels cannot be used on this stove. She took the instruction manual and explained to her mother, that the stove works on magnetic induction, and copper being a dia magnetic material, will not respond to it.
a. What values did Mr.varadan and Dhanya exhibit towards Ms.Sumathy? Mention any two (Awareness, concern for conservation of energy and fossil fuels, sharing the knowledge)
b. Give few examples of diamagnetic materials and explain how their susceptibility varies with temperature?
Answer: Susceptibility is independent of temperature as they have no permanent dipoles.
Question. Bala and Rama class X students were assigned a project based on magnetism. In their project work, they had calculated the value of earth’s magnetic field. When they submitted their project for verification. MrSantosh, their physics teacher, corrected the mistakes. He also suggested few books which could be of use to them.
a. What values did Mr.Santosh exhibit towards his students? Mention any two (Honesty, helpfulness, responsible behaviour towards students, concern for the student to create interest in the subject)
b. Mention the three magnetic elements required to calculate the value of earth’s magnetic field.
Answer: Magnetic declination, magnetic inclination and horizontal component of earth’s magnetic field.
Question. MrSairam the chief development officer, in southern railway went on an official tour to attend a seminar on fast moving trains. He met his friend Ontosaki in Tokyo after he finished his seminar there. His friend explained to Sairam, how Japanese people are concentrating on energy conservation and saving of fossil fuels using Maglev trains. Mr sairam travelled from Tokyo to Osaka in maglev train and found that sound is less, traveliing is smooth and understood in what way we are lagging behind Japanese in mass transporting systems. This works on the principle of Meissner’s effect
(a) What values did Mr sairam found from Ontosaki? Mention any two. (Awareness about new technology, concern for energy conservation, decrease of noise pollution and air pollution i.e, concern for environment)(b) What is Meissner’s effect?
(a) When a superconductor is cooled in a magnetic field below its critical temperature the magnetic field lines are expelled showing diamagnetic property. This is called Meissner effect.
(b) concern for others, helpfulness, presence of mind, responsible citizen
b. What are the roles played by Electric field and magnetic field in Cyclotron?
The charged particles are accelerated by the electric field with the magnetic field bringing them again and again to the electric field that is the region between the ‘Dee’.
Question. Mrs. Gupta family was fast asleep during Night. They had no clue that there living room has caught fire due to a short circuit. Suddenly they heard sound of alarm and woke up. They were surprised to see that the sound was coming from the model of fire alarm prepared by their son. They were all happy that a small science model has saved their life
(i) Give the values displayed by the parents and son.
(ii) Name the device use in the model.
(i) Knowledge, Scientific thinking
(ii) photo cell
Question. Mrs Thakur left her car headlights on while parking. The car would not start when she returned. Seeing her struggle, Mohit went to her help. Not knowing much about cars, he ran and brought a mechanic Raju from a garage nearby. Raju realized that the battery had got discharged as the headlight had been left on for a long time. He brought another battery and connected its terminals to the terminals of the car battery to get the engine started. Once the engine was running, he disconnected this second battery. This is known as “JUMP STARTING”. Mrs. Thakur thanked both Mohit and Raju for helping her.
(i) What values did Mohit have?
(ii) A storage battery of emf 8.0 volts and internal resistance 0.5 ohm is being charged by a 120 volt DC supply using a series resistor of 15.5 ohms. What is the terminal voltage of the battery during charging? What is the purpose of having a series resistor in the charging circuit?
(i) Helpful, aware of his weakness, decision making ability.
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