Explanation:
If two parallel wires carry current in opposite directions, they repel each other whereas if two parallel wires carry current in same direction, they attract each other.
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Energy stored in a coil of self inductance 40mH carrying a steady current of 2 A is
|
(a) 0.8 J |
(b) 8 J |
(c) 0.08 J |
(d) 80 J |
Assertion : Radioactive nuclei emit 
particles.
Reason : Electrons exist inside the nucleus.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
The specific resistance of a wire is ρ, its volume is 3 
and its resistance is 3 ohms, then its length will be
|
(a) |
(b) |
(c) |
(d) |
In Millikan oil drop experiment, a charged drop of mass 1.8 
is stationary between its plates. The distance between its plates is 0.90 cm and potential difference is 2.0 kilo volts. The number of electrons on the drop is
|
(a) 500 |
(b) 50 |
(c) 5 |
(d) 0 |
When a magnet is pushed in and out of a circular coil C connected to a very sensitive galvanometer G as shown in the adjoining diagram with a frequency v, then
|
(a) Constant deflection is observed in the galvanometer |
|
(b) Visible small oscillations will be observed in the galvanometer if v is about 50 Hz |
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(c) Oscillations in the deflection will be observed clearly if v = 1 or 2 Hz |
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(d) No variation in the deflection will be seen if v = 1 or 2 Hz |
A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of
|
(a) Each of these increases |
|
(b) Each of these decreases |
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(c) Copper strip increases and that of germanium decreases |
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(d) Copper strip decreases and that of germanium increases |
