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

If a coil made of conducting wires is rotated between poles pieces of the permanent magnet. The motion will generate a current and this device is called

(a) An electric motor	(b) An electric generator
(c) An electromagnet	(d) All of above

The angle of minimum deviation measured with a prism is 30° and the angle of prism is 60°. The refractive index of prism material is

(a)

(b) 2

(c) 3/2

(d) 4/3

An electron enters a region where electrostatic field is 20N/C and magnetic field is 5T. If electron passes undeflected through the region, then velocity of electron will be

(a)

(b)

(c)

(d)

At room temperature, a P-type semiconductor has

(a) Large number of holes and few electrons

(b) Large number of free electrons and few holes

(c) Equal number of free electrons and holes

(d) No electrons or holes

Diamagnetic substances are

(a) Feebly attracted by magnets	(b) Strongly attracted by magnets
(c) Feebly repelled by magnets	(d) Strongly repelled by magnets

An electron passing through a potential difference of 4.9 V collides with a mercury atom and transfers it to the first excited state. What is the wavelength of a photon corresponding to the transition of the mercury atom to its normal state

(a) 2050 Å

(b) 2240 Å

(c) 2525 Å

(d) 2935 Å

The capacity of a condenser in which a dielectric of dielectric constant 5 has been used, is  C. If the dielectric is replaced by another with dielectric constant 20, the capacity will become

(a)

(b) 4C

(c)

(d) 2C

Two similar cells, whether joined in series or in parallel, same current flows in external resistance of 2. The internal resistance of each cell is:

The Rutherford α-particle experiment shows that most of the α-particles pass through almost unscattered while some are scattered through large angles. What information does it give about the structure of the atom?

When a current I is passed through a wire of constant resistance, it produces a potential difference V across its ends. The graph drawn between log I and log V will be

(a)

(b)

(c)

(d)