Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

In which type of molecule positive and negative charges coincide with each other?

For diffraction of light, it is necessary that the size of the obstacle in comparison to the wavelength of light waves will be :

Direction of induced emf is determined by:

Which of the following is diamagnetism

(a) Aluminium

(b) Quartz

(c) Nickel

(d) Bismuth

A calcite crystal is placed over a dot on a piece of paper and rotated, on seeing through the calcite one will be see

(a) One dot	(b) Two stationary dots
(c) Two rotating dots	(d) One dot rotating about the other

A galvanometer, having a resistance of 50 W gives a full scale deflection for a current of 0.05 A. The length in meter of a resistance wire of area of cross-section 2.97 X 10^–2 cm² that can be used to convert the galvanometer into an ammeter which can read a maximum of 5 A current is (Specific resistance of the wire = 5   Wm)

(a) 9

(b) 6

(c) 3

(d) 1.5

There is some liquid in a closed bottle. The amount of liquid is continuously decreasing. The vapour in the remaining part:

1. Must be saturated.
2. Must be unsaturated.
3. May be saturated.
4. There will be no vapour.

The current through choke coil increases form zero to 6A in 0.3 seconds and an induced e.m.f. of 30 V is produced. The inductance of the coil of choke is

(a) 5 H

(b) 2.5 H

(c) 1.5 H

(d) 2 H

The respective radii of the two spheres of a spherical condenser are 12 cm  and 9 cm. The dielectric constant of the medium between them is 6. The capacity of the condenser will be

(a) 240 pF

(b) 240 μF

(c) 240 F

(d) None of the above

If the wavelength of light is 4000 Å, then the number of waves in 1 mm length will be

(a) 25

(b) 0.25

(c) 0.25

(d) 25