Electromagnetic Induction — Physics STD 12 Science — Question

An electron makes a transition from orbit n = 4 to the orbit n = 2 of a hydrogen atom. The wave number of the emitted radiations (R = Rydberg's constant) will be

(a)

(b)

(c)

(d)

In electromagnetic wave, according to Maxwell, changing electric field gives.

In a projectile motion the velocity:

1. Is always perpendicular to the acceleration.
2. Is never perpendicular to the acceleration.
3. Is perpendicular to the acceleration for one instant only.
4. Is perpendicular to the acceleration for two instants.

The potential difference across the 100 W resistance in the following circuit is measured by a voltmeter of 900 W resistance. The percentage error made in reading the potential difference is

(a)

(b) 0.1

(c) 1.0

(d) 10.0

 A star emitting radiation at a wavelength of 5000 Å is approaching earth with a velocity of 1.5. The change in wavelength of the radiation as received on the earth, is

(a) 25 Å

(b) Zero

(c) 100 Å

(d) 2.5 Å

An infinitely long straight conductor is bent into the shape as shown in the figure. It carries a current of i ampere and the radius of the circular loop is r metre. Then the magnetic induction at its centre will be

(a)

(b)

(c) Zero

(d) Infinite

To reduce the value of capacitance of a parallel plate capacitor, the empty space between the plates:

Fusion reaction take place at high temperature because:

You are given several identical resistances each of value R = 10 Ω  and each capable of carrying maximum current of 1 ampere. It is required to make a suitable combination of these resistances to produce a resistance of  5 Ω which can carry a current of 4 amperes. The minimum number of resistances of the type R that will be required for this job

(a) 4

(b) 10

(c) 8

(d) 20