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

To form a composite 16Μf, 1000 V  capacitor from a supply of identical capacitors marked 8 μF, 250 V we require a minimum number of capacitors

(a) 40

(b) 32

(c) 8

(d) 2

Quantam nature of light is explained by which of the following phenomenon

(a) Huygen wave theory	(b) Photoelectric effect
(c) Maxwell electromagnetic theory	(d) de-Broglie theory

Four condensers are joined as shown in the adjoining figure. The capacity of each is 8 μF. The equivalent capacity between the points A and  B will be

(a) 32  μF

(b) 2 μF

(c) 8 μF

(d) 16 μF

A hollow copper sphere A and a solid sphere B of equal radius are charged with the same potential. The true statement is:

The sun emits a light with maximum wavelength 510 mm while another star X emits a light with maximum wavelength of 350 nm. What is the ratio of surface temperature of sun and the star X

(a) 2.1

(b) 0.68

(c) 0.46

(d) 1.45

Electromagnets are made of soft iron because soft iron has:

1. High retentivity and high coercive force.
2. High retentivity and low coercive force.
3. Low retentivity and high coercive force.
4. Low retentivity and low coercive force.

Line spectrum contains information about

(a) The atoms of the prism

(b) The atoms of the source

(c) The molecules of the source

(d) The atoms as well as molecules of the source

Identify the process in which an electron escapes from the metal surface.

An atom of nuclean change q is placed on a line. There particles A(mass = m, change = q), B(mass = 2, change =q) and C(mass = 3m, change = 3q) are shot towards the atom, a distance r away from the line and parallel to it. The particle that would be deflected the most would be?

Two opposite and equal charges 4 ×   when placed 2  cm away, form a dipole. If this dipole is placed in an external electric field 4 ,  the value of maximum torque and the work done in rotating it through 180°  will be

(a) 64  and  64	(b) 32   and 32
(c) 64  and 32	(d) 32  and 64