CBSE Class 10 Physics Electricity Worksheet Set 05

A printable Class 10 Physics worksheet on Electricity with fill in the blanks, true or false statements and short numericals, all with answers. It is a quick revision of current, resistance, Ohm's law, power and fuses without any diagrams.

Fill in the Blanks

Question 1. Fill in the blank: The rate of flow of electric charge is called ________.
Answer:
Electric current (I = Q/t).
In simple words: Current is charge per second.

Teacher's Note:
1. Unit: ampere.
2. I = Q/t.

Question 2. Fill in the blank: If there is no current, a voltmeter connected across a resistor will register ________ voltage.
Answer:
Zero voltage, because V = IR and I = 0.
In simple words: No current means no potential drop.

Teacher's Note:
1. Use V = IR.
2. I = 0 gives V = 0.

Question 3. Fill in the blank: Combined resistance is the sum of separate resistances provided that the various conductors are connected in ________.
Answer:
Series.
In simple words: Resistances add in series.

Teacher's Note:
1. R_s = R₁ + R₂ + R₃.
2. In parallel, reciprocals add.

Question 4. Fill in the blank: In a parallel circuit, each circuit element has the same ________.
Answer:
Potential difference (voltage).
In simple words: Parallel branches share the same voltage.

Teacher's Note:
1. Current divides, voltage is common.
2. Series has the same current.

Question 5. Fill in the blank: Copper is a preferred material for making wire because of its low ________.
Answer:
Resistivity (resistance).
In simple words: Low resistivity means little loss of energy.

Teacher's Note:
1. Copper has a resistivity of 1.62 × 10⁻⁸ Ω m.
2. Silver is better but costly.

Question 6. Fill in the blank: The S.I. unit of resistance is ________.
Answer:
Ohm (Ω).
In simple words: The unit of resistance is the ohm.

Teacher's Note:
1. 1 Ω = 1 V/A.
2. Named after Georg Ohm.

Question 7. Fill in the blank: 1 volt × 1 coulomb = ________.
Answer:
1 joule, since V = W/Q.
In simple words: A volt is a joule per coulomb.

Teacher's Note:
1. V = W/Q.
2. Work = QV.

Question 8. Fill in the blank: Potential difference is a ________ quantity.
Answer:
Scalar.
In simple words: It has magnitude but no direction.

Teacher's Note:
1. Current is also treated as a scalar.
2. Force is a vector.

Question 9. Fill in the blank: The physical quantity represented by coulomb per second is ________.
Answer:
Electric current (ampere).
In simple words: 1 A = 1 C/s.

Teacher's Note:
1. I = Q/t.
2. SI unit: ampere.

Question 10. Fill in the blank: Two resistances of 2 Ω each are connected in parallel. The equivalent resistance is ________.
Answer:
1/R = 1/2 + 1/2 = 1, so R = 1 Ω.
In simple words: Two equal resistors in parallel give half.

Teacher's Note:
1. R = r/2.
2. Parallel R is smaller.

True or False

Question 11. State whether true or false: The quantity of charge flowing through a point multiplied by time is a current.
Answer:
False. Current is the charge flowing per unit time, I = Q/t. (Charge multiplied by time has no such meaning.)
In simple words: Current is charge divided by time.

Teacher's Note:
1. I = Q/t.
2. Correct the statement.

Question 12. State whether true or false: The resistivity of all pure metals increases with the rise in temperature.
Answer:
True. The atoms vibrate more at higher temperature, so the free electrons are obstructed more.
In simple words: Hot metals resist current more.

Teacher's Note:
1. Alloys change very little.
2. Link with collisions.

Question 13. State whether true or false: Ohm’s law is a relation between the power used in a circuit to the current and the potential difference.
Answer:
False. Ohm's law relates the potential difference and the current: V = IR (at constant temperature). Power is P = VI.
In simple words: Ohm's law links V and I, not power.

Teacher's Note:
1. State Ohm's law correctly.
2. P = VI is a different relation.

Question 14. State whether true or false: The direction of current is taken opposite to the direction of flow of electrons.
Answer:
True. Conventional current is the direction of flow of positive charge, from the positive to the negative terminal, opposite to the flow of electrons.
In simple words: Conventional current is opposite to electron flow.

Teacher's Note:
1. Electrons are negative.
2. Current flows from + to − outside the cell.

Question 15. State whether true or false: The series arrangement is used for domestic circuits.
Answer:
False. Domestic circuits use parallel connection, so that each appliance gets the full voltage and works independently.
In simple words: Homes are wired in parallel.

Teacher's Note:
1. State why series is unsuitable.
2. Parallel allows separate switches.

Question 16. State whether true or false: The filament resistance of a glowing bulb is greater than its resistance when it is not glowing.
Answer:
True. A glowing filament is at a very high temperature, and the resistance of a metal increases with temperature.
In simple words: Hot filament, higher resistance.

Teacher's Note:
1. Compare R = V/I when cold and hot.
2. Metals: resistance increases with temperature.

Numerical Questions

Question 17. A lamp of resistance 80 Ω draws a current of 0.75 A. Find the line voltage.
Answer:
V = IR = 0.75 × 80 = 60 V.
In simple words: Voltage = current × resistance.

Teacher's Note:
1. Apply Ohm's law.
2. Unit: volt.

Question 18. An electric heater draws a current of 5 A when connected to 220 V mains. Calculate the resistance of its filament.
Answer:
R = V/I = 220/5 = 44 Ω.
In simple words: Resistance = voltage ÷ current.

Teacher's Note:
1. Ohm's law: R = V/I.
2. Unit: ohm.

Question 19. An electric bulb draws a current of 0.25 A for 20 minutes. Calculate the electric charge that flows through the circuit.
Answer:
t = 20 × 60 = 1200 s.
Q = It = 0.25 × 1200 = 300 C.
In simple words: Charge = current × time.

Teacher's Note:
1. Change minutes to seconds.
2. Q = It.

Question 20. If the amount of electric charge passing through a conductor in 10 min is 300 C, find the current.
Answer:
t = 10 × 60 = 600 s.
I = Q/t = 300/600 = 0.5 A.
In simple words: Current = charge ÷ time.

Teacher's Note:
1. Time must be in seconds.
2. I = Q/t.

Question 21. What is the resistance of an electric arc lamp when hot, if the lamp uses 20 A when connected to a 220 V line?
Answer:
R = V/I = 220/20 = 11 Ω.
In simple words: A hot arc lamp has 11 Ω resistance.

Teacher's Note:
1. Use R = V/I.
2. Check the units.

Question 22. Determine the p.d. which must be applied to a 2 kΩ resistor in order that a current of 10 mA may flow.
Answer:
R = 2 kΩ = 2000 Ω; I = 10 mA = 0.01 A.
V = IR = 0.01 × 2000 = 20 V.
In simple words: Convert kΩ and mA to SI units.

Teacher's Note:
1. 1 kΩ = 1000 Ω.
2. 1 mA = 10⁻³ A.

Question 23. A bulb of resistance 400 Ω is connected to 220 V mains. Calculate the magnitude of current.
Answer:
I = V/R = 220/400 = 0.55 A.
In simple words: Current = voltage ÷ resistance.

Teacher's Note:
1. Use Ohm's law.
2. Unit: ampere.

Question 24. A steady current of 5 A flows through a circuit for 30 minutes. How much charge has circulated through the circuit in this time?
Answer:
t = 30 × 60 = 1800 s.
Q = It = 5 × 1800 = 9000 C.
In simple words: Charge = current × time.

Teacher's Note:
1. Convert minutes to seconds.
2. Q = It.