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

In a P-type semi-conductor, germanium is dopped with

(a) Gallium

(b) Boron

(c) Aluminium

(d) All of these

The amplification factor of a triode is 20 and trans-conductance is 3 milli mho and load resistance 3   then the voltage gain is

(a) 16.36

(b) 28

(c) 78

(d) 108

 If the wavelength of electromagnetic radiation is doubled, what will happen to the energy of photons?

1 Pico farad =

The work function of a metal is hv_0. Light of frequency v falls on this metal. The photoelectric effect will take place only if:

The permanent magnetic moment of the atoms of a material is not zero. The material:

1. Must be paramagnetic.
2. Must be diamagnetic.
3. Must be ferromagnetic.
4. May be paramagnetic.

A small magnet is placed perpendicular to a uniform magnet field. The forces acting on the magnet will result in:

The resistance of a coil is 4.2 Ω at 100 ^oC and the temperature coefficient of resistance of its material is 0.004/^o C.  Its resistance at 0^o C is

(a) 6.5 Ω

(b) 5 Ω

(c) 3 Ω

(d) 4 Ω

Electric charge is measured in:

A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will

(a) Get deflected vertically upwards

(b) Move in a circular orbit with its speed increased

(c) Move in a circular orbit with its speed unchanged

(d) Continue to move due east