Science worksheet:02
Lesson : Electricity
Section A: Multiple Choice Questions (MCQs) (1 Mark Each)
1.The S.I. unit of electric current is:
(a) Ohm (b) Ampere (c) Volt (d) Coulomb
2.Which of the following is not a good conductor of electricity?
(a) Copper (b) Aluminium (c) Wood (d) Graphite
3.The relationship between potential difference (V), current (I), and resistance (R) is given by:
(a) I=VR (b) V=IR (c) R=VI (d) V=I/R
4.A device used to measure potential difference is:
(a) Ammeter (b) Voltmeter (c) Galvanometer (d) Rheostat
5.When resistors are connected in series, the equivalent resistance is:
(a) Less than the smallest individual resistance
(b) Greater than the largest individual resistance
(c) Equal to the average of individual resistances
(d) Always the sum of individual resistances
6. Electric power is given by:
2 2 2
(a) P=V/I (b) P=I R (c) P=R/I (d) P=V I
7.The commercial unit of electrical energy is:
(a) Joule (b) Kilowatt-hour (c) Watt (d) Erg
8. Fuse wire is made of an alloy of:
(a) Copper and Aluminium (b) Lead and Tin (c) Nichrome (d) Copper and Nickel
Section B: Assertion and Reason Questions (1Marks Each)
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
9. Assertion (A): The resistance of a conductor increases with an increase in its temperature.
Reason (R): When temperature increases, the atoms in the conductor vibrate more vigorously,
hindering the flow of electrons.
10. Assertion (A): Copper is used to make electric wires.
Reason (R): Copper has very low resistivity.
11. Assertion (A): For a parallel combination of resistors, the equivalent resistance is smaller
than the smallest individual resistance.
Reason (R): In a parallel combination, the current divides among the branches, effectively
increasing the cross-sectional area for current flow.
12. Assertion (A): Heating effect of current is utilised in an electric bulb.
Reason (R): The filament of an electric bulb is made of a material with high melting point and
high resistance.
Section C: Short Answer Questions (2-3 Marks Each)
13. Define electric current and state its S.I. unit.
14. What is potential difference? Name the device used to measure it and how is it connected in
a circuit?
15. State Ohm's Law. Draw a V-I graph for an ohmic resistor and non-ohmic resistor.
16. Why are heating elements of electric toasters and electric irons made of an alloy rather than
a pure metal?
Section D: Numerical Problems (3-5 Marks Each)
17. A current of 0.5 A is drawn by a filament of an electric bulb for 10 minutes. Find the amount
of electric charge that flows through the circuit.
18. (a) Three resistors 2Ω, 3Ω and 6Ω are connected in parallel. What is the equivalent
resistance of the combination?
(b) If the combination is connected to a 6 V battery, calculate the current flowing through each
resistor and the total current drawn from the battery.
19. (a) Draw a schematic diagram of a circuit consisting of a battery of 6 V, a 5Ω resistor, an 8Ω
resistor, and a 12Ω resistor, and a plug key, all connected in series.
(b) Recalculate the equivalent resistance of the circuit.
(c) Calculate the total current flowing in the circuit.
(d) Calculate the potential difference across the 8Ω resistor.
Section E: Application/HOTS Questions (3-4 Marks Each)
20. An electric fuse is a safety device used in electric circuits.
(a) What is the principle of working of an electric fuse?
(b) What characteristics should a material for a fuse wire have?
(c) Why are fuses always connected in the live wire of the main circuit?
21. Why are domestic circuits connected in parallel arrangement and not in series? Give three
reasons.
********************************_______________________________**********************************
