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

If a number of sine waves with modulation indices n₁, n₂, n₃ ........ modulate a carrier wave, then total modulation index (n) of the wave is

(a) n1 + n2 .... + 2(n1 + n2.....)	(b)
(c)	(d) None of these

A plane electromagnetic wave propagating along x direction can have the following pairs of E and B.

The earth’s magnetic field always has a vertical component except at the:

Which instrument is used as the null detector in the Wheatstone bridge?

The equation of an alternating voltage is E = 220 E = 220.Then the impedance of the circuit is:

Which is the correct diagram of a half-wave rectifier

(a)	(b)
(c)	(d)

The order of magnitude of radius of nucleus is ___________.

Assertion :   An artificial satellite with a metal surface is moving above the earth in a circular orbit. A current will be induced in satellite if the plane of the orbit is inclined to the plane of the equator.

Reason     : The current will be induced only when the speed of satellite is more than 8 km/sec.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Ultraviolet rays coming from sun are absorbed by:

A short magnet oscillates with a time period 0.1 s at a place where horizontal magnetic field is 24μT. A downward current of 18 A is established in a vertical wire 20 cm east of the magnet. The new time period of oscillator

(a) 0.1 s

(b) 0.089 s

(c) 0.076 s

(d) 0.057 s