Radiation and Dual Nature of Matter — Physics STD 12 Science — Question

Consider the two idealized systems: (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L > > R, radius of cross-section. In (i) E is ideally treated as a constant between plates and zero outside. In (ii) magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as below:

Heavy water is used as moderator in a nuclear reactor. The function of the moderator is

(a) To control the energy released in the reactor

(b) To absorb neutrons and stop chain reaction

(c) To cool the reactor faster

(d) To slow down the neutrons to thermal energies

Optical fibre communication is based on which of the following phenomena :

For nuclei with A > 100:

1. The binding energy of the nucleus decreases on an average as A increases.
2. The binding energy per nucleon decreases on an average as A increases.
3. If the nucleus breaks into two roughly equal parts, energy is released.
4. If two nuclei fuse to form a bigger nucleus, energy is released.

Assertion :   A transformer cannot work on dc supply.

Reason     : dc changes neither in magnitude nor in direction.

(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.

In Young’s double slit experiment, the intensity of light coming from the first slit is double the intensity from the second slit. The ratio of the maximum intensity to the minimum intensity on the interference fringe pattern observed is

(a) 34

(b) 40

(c) 25

(d) 38

A thin glass (refractive index 1.5) lens has optical power of -5D in air. It's optical power in a liquid medium with refractive index 1.6 will be

(a) 25 D

(b) – 25 D

(c) 1 D

(d) None of these

Unpolarized light falls on two polarizing sheets placed one on top of the other. What must be the angle between the characteristic directions of the sheets if the intensity of the final transmitted light is one-third the maximum intensity of the first transmitted beam

(a) 75°

(b) 55°

(c) 35°

(d) 15°

In the circuit shown in the figure, the current through

(a) The 3 W resistor is 0.50A	(b) The 3 W resistor is 0.25 A
(c) The 4 W resistor is 0.50A	(d) The 4 W resistor is 0.25 A

When a ferromagnetic material goes through a hysteresis loop, the magnetic susceptibility: