Moving Charges and Magnetism — Physics STD 12 Science — Question

A ray of monochromatic light is incident on one refracting face of a prism of angle 75°. It passes through the prism and is incident on the other face at the critical angle. If the refractive index of the material of the prism is , the angle of incidence on the first face of the prism is

(a) 30°

(b) 45°

(c) 60°

(d) 0°

The filament of an electric bulb is made of:

p-n junction diode acts as:

Assertion   :   Two electric bulbs of 50 and 100 W are given. When connected in series 50 W bulb glows more but when connected parallel 100 W bulb glows more. 

Reason      : In series combination, power is directly proportional to the resistance of circuit. But in parallel combination, power is inversely proportional to the resistance of the circuit.

(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.

An electron is moving along the positive X-axis. You want to apply a magnetic field for a short time so that the electron may reverse its direction and move parallel to the negative X-axis. This can be done by applying the magnetic field along

(a) Y-axis

(b) X-axis

(c) Y-axis only

(d) None of these

A ferromagnetic material is heated above its curie temperature. Which one is a correct statement

(a) Ferromagnetic domains are perfectly arranged

(b) Ferromagnetic domains becomes random

(c) Ferromagnetic domains are not influenced

(d) Ferromagnetic material changes itself into diamagnetic material

In Fig, Vo is the potential barrier across a p-n junction, when no battery is connected across the junction:

Let T_a and T_b be the final temperatures of the samples A and B, respectively, in the previous question.

1. T_a < T_b
2. T_a = T_b
3. T_a > T_b
4. The relation between T_a and T_b cannot be deduced.

A heave uniform rod Is hanging vertically form a foxed support. It is stretched by its won weight. The diameter of the rod is.

1. Smallest at the top and gradually increases down the rod.
2. Largest at the top and gradually decreased down the rod.
3. Uniform everywhere.
4. Maximum in the middle.

A pure resistor is joined with a capacitor. The magni- tude of tangent of their phase difference in the cir- cuit is: