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

The bottom of a container filled with liquid appear slightly raised because of

(a) Refraction

(b) Interference

(c) Diffraction

(d) Reflection

To obtain P-type Si semiconductor, we need to dope pure Si  with

(a) Aluminium

(b) Phosphorous

(c) Oxygen

(d) Germanium

A bar magnet is released from rest along the axis of a very long, vertical copper tube. After some time the magnet:

1. Will stop in the tube.
2. Will move with almost content speed.
3. Will move with an acceleration g.
4. Will oscillate.

If λ =10Å, then it corresponds to

(a) Infra-red

(b) Microwave

(c) Ultra-violet

(d) X-rays

A thermo couple uses Bismuth and Tellurium as the dissimilar metals. The sensitivity of bismuth is -72μV/℃  and that of the tellurium is 500μV/℃. If the difference between hot and cold junction is 100℃  then the maximum output will be

(a) 50 mV

(b) 7.2 mV

(c) 42.8 mV

(d) 57.2 mV

The ratio of intensities of consecutive maxima in the diffraction pattern due to a single slit is

(a) 1 : 4 : 9

(b) 1 : 2 : 3

(c) 1 :

(d) 1 :

The particles emitted by radioactive decay are deflected by magnetic field. The particles will be

(a) Protons and α - particles	(b) Electrons, protons and α -particles
(c) Electrons, protons and neutrons	(d) Electrons and α -particles

The efficiency of transformer is very high because

(a) There is no moving part in a transformer	(b) It produces very high voltage
(c) It produces very low voltage	(d) None of the above

At magnetic poles, the angle of dip is:

Equal torques act on the discs A and B of the previous problem, initially both being at rest. At a later instant, the linear speeds of a point on the rim of A and another point on the rim of B are v_A and v_B respectively. We have:

1. v_A > v_B
2. v_A = v_B
3. v_A < v_B
4. The relation depends on the actual magnitude of the torques.