Wave Motion and Waves on a String — Physics STD 12 Science — Question

When a P - N junction is unbiased, the junction current at equilibrium is:

Dimensions of coefficient of self-inductance is :

The mean electric energy density between the plates of a charged capacitor is (here q = charge on the capacitor and  A = area of the capacitor plate)

(a)

(b)

(c)

(d) None of the above

The gate for which output is high, if at least one input is low is:

Assertion :  The setting sun appears to be red.

Reason     :  Scattering of light is directly proportional to the wavelength.

(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.

A solid floats in a liquid in a partially dipped position.

1. The solid exerts a force equal to its weight on the liquid.
2. The liquid exerts a force of buoyancy on the solid which is equal to the weight of the solid.
3. The weight of the displaced liquid equals the weight of the solid.
4. The weight of the dipped part of the solid is equal to the weight of the displaced liquid.

Forty electric bulbs are connected in series across a 220 V supply. After one bulb is fused, the remaining 39 are connected again in series across the same supply. The illumination will be

(a) More with 40 bulbs than with 39	(b) More with 39 bulbs than with 40
(c) Equal in both the cases	(d) In the ratio of

Constructive and destructive interference occur in:

On moving a charge of Q coulomb by X cm, W J of work is done, then the potential difference between the points is: