11. |
Masses of three wires of copper are in the ratio 5 : 3 : 1 and their lengths are in the ratio 1 : 3 : 5. The ratio of their electrical resistances are _____.
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Answer:
Option (c) |
12. |
The resistance of a 10 m long potentiometer wire is 20 Ω. It is connected in series with a 3 V battery and 10 Ω resistor. The potential difference between two points separated by distance 30 cm is equal to _____ .
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Answer:
Option (b) |
13. |
n identical cells each of emf ε and internal resistance r are connected in parallel with resistor R. The current flowing through resistor R is, _____ .
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Answer:
Option (b) |
14. |
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Answer:
Option (b) |
15. |
If the current in an electric bulb increases by 1 %, what will be the change in the power of a bulb ?
[Assume that the resistance of the filament of a bulb remains constant.]
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Answer:
Option (c) |
16. |
Two bulbs of 220 V and 100 W are first connected in series and than in parallel with supply of 220 V. Total power in both the cases will be _____ .
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Answer:
Option (d) |
17. |
In a hydrogen atom, the electron is moving in a circular orbit of radius 5.3 x 10-11 m with a constant speed of 2.2 x 106 ms-1. The electric current formed due to the motion of electron is _____
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Answer:
Option (b) |
18. |
A ring of radius R and linear charge density λ on its surface is performing rotational motion about an axis perpendicular to its plane. If the angular velocity of the ring is ω, how much current is constituted by the ring ?
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Answer:
Option (a) |
19. |
A cell supplies a current of 0.9 A through a 2 Ω resistor and current of 0.3 A through a 7 Ω resistor. What is the internal resistance of the cell ?
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Answer:
Option (a) |
20. |
A current density of 2.5 Am-2 is found to exist in a conductor when an electric field of 5 x 10-8 Vm-1 is applied across it. The resistivity of a conductor is _____
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Answer:
Option (b) |