CBSE - Electricity

1 Electricity A wire of resistance R is stretched to twice of its original length. Its new resistance will be :

(1) 4R
(2) R / 4
(3) 2R
(4) R / 2

2 Electricity If current through a resistance is increased by 100% simultaneously reducing resistance value to 25%, the new power
dissipated will be
(1) No change
(2) Increased by 100%
(3) Decreased by 400%
(4) Increased by 400%

3 Electricity One Volt is equal to -

(1) 1 Joule
(2) 1 Newton/Coulomb
(3) 1 Joule/Coulomb
(4) 1 Coulomb/Newton

4 Electricity Two wires each carrying current i are shown. The magnetic field at P (midway between the wires) is described by which statement?



(1) Magnetic fields are in opposite direction and net field is equal to zero.
(2) Magnetic fields due to two wires are in the same direction
(3) Magnetic fields are in opposite direct ion but net field is not zero
(4) magnetic fields are in the same direction and equal to two times the field due to one wire.

5 Electricity The unit of electrical energy is

(1) watt
(2) killowatt
(3) kilowatt per hour
(4) kilowatt hour

6 Electricity Out of two bulbs 50 W – 220 V and 100 W –220 V, which one will glow brighter

(a) When connected in series

(b) When connected in parallel

(1) (a) 100 W, (b) 50 W
(2) (a) 50W, (b) 100 W
(3) (a) both will glow similar (b) 100 W
(4) none of t he above

7 Electricity Alloys are commonly used in electrical heat ing devices, like electric iron etc. because -

(1) Alloys have higher resistivity than that of its constituent metals.
(2) Alloys do not burn at higher temperatures.
(3) Alloys do not oxidise at higher temperatures.
(4) All of above.

8 Electricity 

An ammeter can read current upto 5 A and it has twenty divisions between the mark 0 and mark 2A on its scale

The least count of the ammeter is

(1) 0.02 A
(2) 0.01 A
(3) 0.2 A
(4) 0.1 A

9 Electricity What is the equivalent resistance of the following arrangement between M and N



(1) R/2
(2) R/3
(3) R/4
(4) R/6

10 Electricity The power of electric power station is 200 mega watt , the elect rical energy produced by it daily will be

(1) 200 megawatt hour
(2) 4800 megawatt hour
(3) 4800 megawatt
(4) 4800 joule