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

A transformer is based on the principle of

(a)  Mutual inductance	(b) Self  inductance
(c)  Ampere's law	(d) Lenz's law

A closed surface S is constructed around a conducting wire connected to a battery and a switch (figure). As the switch is closed, the free electrons in the wire start moving along the wire. In any time interval, the number of electrons entering the closed surface S is equal to the number of electrons leaving it. On closing the switch, the flux of the electric field through the closed surface:

1. Is increased.
2. Is decreased.
3. Remains unchanged.
4. Remains zero.

Three capacitances of capacity 10 μF, 5 μF  and 5 μF  are connected in parallel. The total capacity will be

(a) 10 μF

(b) 5 μF

(c) 20 μF

(d) None of the above

The pole pieces of the magnet used in a pivoted coil galvanometer are

(a) Plane surfaces of a bar magnet

(b) Plane surfaces of a horse-shoe magnet

(c) Cylindrical surfaces of a bar magnet

(d) Cylindrical surfaces of a horse-shoe magnet

A particle is dropped from a height H. The de Broglie wavelength of the particle as a function of height is proportional to:

Two charges are placed a certain distance apart in air. If a brass plate is introduced between them, the force between them will:

Huygens principle of secondary waves:

The frequency of radio waves corresponding to a wavelength of 10m is:

For germanium diode, the junction voltage is about _____.