Wave Optics — Physics STD 12 Science — Question

A galvanometer with a resistance of 12 W gives full scale deflection when a current of 3 mA is passed. It is required to convert it into a voltmeter which can read up to 18 V.  the resistance to be connected is

(a) 6000 W

(b) 5988 W

(c) 5000 W

(d) 4988 W

What happens to the capacitance when a dielectric material is inserted between the plates of a parallel plate capacitor?

Two slits, 4 mm apart, are illuminated by light of wavelength 6000 Å. What will be the fringe width on a screen placed 2m from the slits

(a) 0.12 mm

(b) 0.3 mm

(c) 3.0 mm

(d) 4.0 mm

The heat generated through 2 ohm and 8 ohm resistances separately, when a condenser of 200 μF capacity charged to 200 V is discharged one by one, will be

(a) 4 J and 16 J respectively	(b) 16 J and 4 J respectively
(c) 4 J and 8 J respectively	(d) 4 J and 4 J respectively

Which of the following sources gives best monochromatic light?

1. A candle.
2. A bulb.
3. A mercury tube.
4. A laser.

Which resistor is difficult to make of having a value less than about 2 Ohms?

The ratio of the forces between two small spheres with constant charge (a) in air (b) in a medium of dielectric constant K is

(a) 1 : K

(b) K : 1

(c)

(d)

The device that does not work on the principle of mutual induction is

(a) Induction coil

(b) Motor

(c) Tesla coil

(d) Transformer

Quantisation of charge implies: