Moving Charges and Magnetism — Physics STD 12 Science — Question

When the modulating frequency is doubled, the modulation index is halved and the modulating voltage remains constant, the modulation system is

(a) Amplitude modulation	(b) Phase modulation
(c) Frequency modulation	(d) All of the above

Refractive index of air is 1.0003. The correct thickness of air column which will have one more wavelength of yellow light (6000 Å) than in the same thickness in vacuum is

(a) 2 mm

(b) 2 cm

(c) 2 m

(d) 2 km

A small bar magnet of moment M is placed in a uniform field H. If magnet makes an angle of 30° with field, the torque acting on the magnet is

(a) MH

(b)

(c)

(d)

50 Ω and 100 Ω  resistors are connected in series. This connection is connected with a battery of 2.4 volts. When a voltmeter of 100 Ω  resistance is connected across 100 Ω  resistor, then the reading of the voltmeter will be

(a) 1.6 V

(b) 1.0 V

(c) 1.2 V

(d) 2.0 V

Like charges ____ each other.

A parallel plate capacitor has a plate separation of 0.01 mm and use a dielectric (whose dielectric strength is 19 KV/mm) as an insulator. The maximum potential difference that can be applied to the terminals of the capacitor is

(a) 190 V

(b) 290 V

(c) 95 V

(d) 350 V

In angle of prism and angle of minimum deviation each is A then the refractive index of the material of the prism will be :

A small square loop of wire of side l is placed inside a large square loop of wire of side L (L > l). The loop are coplanar and their centre coincide. The mutual inductance of the system is proportional to

(a) l / L

(b)

(c) L/l

(d)

Two solenoids have identical geometrical construction but one is made of thick wire and the other of thin wire. Which of the following quantities are different for the two solenoids?

1. Self-inductance.
2. Rate of Joule heating if the same current goes through them.
3. Magnetic field energy if the same current goes through them.
4. Time constant if one solenoid is connected to one battery and the other is connected to another battery.