Current Electricity — Physics STD 12 Science — Question

The angular velocity of the engine (and hence of the wheel) of a scooter is proportional to the petrol input per second. The scooter is moving on a frictionless road with uniform velocity. If the petrol input is increased by 10%, the linear velocity of the scooter is increased by:

1. 50%
2. 10%
3. 20%
4. 0%

Assertion  :  Microwave communication is preferred over optical communication.
Reason      : Microwaves provide large number of channels and band width compared to optical signals. (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.

Among which of the following the magnetic susceptibility does not depend on the temperature?

The frequency of the incident light falling on a photosensitive metal plate is doubled, the kinetic energy of the emitted photoelectrons is(a) Double the earlier value(b) Unchanged(c) More than doubled(d) Less than doubled

How many spectral lines does hydrogen have?

If a copper rod carries a direct current, the magnetic field associated with the current will be:

Two coherent monochromatic light beams of intensities I  and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are(a) 5I and I(b) 5I and 3I(c) 9I and I(d) 9I and 3I

For goldplating on a copper chain, the substance required in the form of solution is(a) Copper sulphate(b) Copper chloride(c) Potassium cyanide(d) Potassium aurocyanide