Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

A ray of light is incidenting normally on a plane mirror. The angle of reflection will be(a) 0°(b) 90°(c) Will not be reflected(d) None of the above

At low frequency a condenser offers:

A transmitter supplies 9 kW to the aerial when unmodulated. The power radiated when modulated to 40% is (a) 5 kW(b) 9.72 kW(c) 10 kW(d) 12 kW

In an elastic collision:

1. The initial kinetic energy is equal to the final kinetic energy.
2. The final kinetic energy is less than the initial kinetic energy.
3. The kinetic energy remains constant.
4. The kinetic energy first increases then decreases.

Antimony and bismuth are usually used in a thermocouple, because(a) Negative thermal e.m.f. produced(b) Constant thermal e.m.f. produced(c) Lower thermal e.m.f. produced(d) Higher thermal e.m.f. produced

The focal length of the field lens (which is an achromatic combination of two lenses) of telescope is 90 cm. The dispersive powers of the two lenses in the combination are 0.024 and 0.036. The focal lengths of two lenses are(a) 30 cm and 60 cm(b) 30 cm and – 45 cm(c) 45 cm and 90 cm  (d) 15 cm and 45 cm

Two parallel wires carry currents of 20A and 40A in opposite directions. Another wire carying a current anti parallel to 20A is placed midway between the two wires. T he magnetic force on it will be:

A parallel plate capacitor consists of two circular plates each of radius 12cm and separated by 5.0mm. The capacitor is being charged by an external source. The charging current is constant and is equal to 0.15A.The displacement current is:

A wire loop is rotated in a uniform magnetic field about an axis perpendicular to the field. The direction of the current induced in the loop reverse once each.