Electromagnetic Waves — Physics STD 12 Science — Question

Coulomb's Law is true for:

The figure shows three circuits with identical batteries, inductors, and resistors. Rank the circuits according to the current through the battery (i) just after the switch is closed and (ii) a long time later, greatest first

(a) (i)  (ii)

(b) (i)   (ii)

(c) (i)  (ii)

(d) (i)  (ii)

Two coherent light sources S₁ and S₂ (l= 6000 Å) are 1mm apart from each other. The screen is placed at a distance of 25 cm from the sources. The width of the fringes on the screen should be

(a) 0.015 cm

(b) 0.025 cm

(c) 0.010 cm

(d) 0.030 cm

Symbol of Inductance in electric circuit is-

A cell of e.m.f. E is connected with an external resistance R, then p.d. across cell is V. The internal resistance of cell will be

(a)

(b)

(c)

(d)

In the following circuit, the bulb will become suddenly bright if

(a) Contact is made or broken	(b) Contact is made
(c) Contact is broken	(d) Won't become bright at all

An artificial radioactive decay series begins with unstable . The stable nuclide obtained after eight α - decays and five β- decays is

(a)

(b)

(c)

(d)

The time taken by sunlight to cross a 5 mm thick glass plate (μ = 3/2) is

(a) 0.25

(b) 0.167

(c) 2.5

(d) 1.0

A varying current in a coil change from 10A to 0 in 0.5sec. If the average emf induced in the coil is 220V, the self inductance of the coil is:

Total electric flux coming out of a unit positive charge put in air is

(a)

(b)

(c)

(d) 4π