Alternating Current — Physics STD 12 Science — Question

An object can be negatively charged by:

In two separate set - ups of the Young's double slit experiment, fringes of equal width are observed when lights of wavelengths in the ratio 1 : 2 are used. If the ratio of the slit separation in the two cases is 2 : 1, the ratio of the distances between the plane of the slits and the screen in the two set - ups is

(a) 4 : 1

(b) 1 : 1

(c) 1 : 4

(d) 2 : 1

The minimum energy required to excite a hydrogen atom from its ground state is

(a) 13.6 eV

(b) -13.6 eV

(c) 3.4 eV

(d) 10.2 eV

The coefficient of mutual induction between two coils is 4H. If the current in the primary reduces from 5A to zero in 10^-3 second then the induced emf in the secondary coil will be

An electric dipole of moment    placed in a uniform electric field   has minimum potential energy when the angle between   and   is

(a) Zero

(b)

(c) π

(d)

The wavelength of most energetic X-rays emitted when a metal target is bombarded by 40KeV  electrons, is approximately  (h = 6.63 )

(a) 300 Å

(b) 10 Å

(c) 4 Å

(d) 0.31 Å

X-rays are produced in X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays has values from

(a) 0 to ∞

(b)   to ∞, where

(c) 0  to   where

(d)  to , where 0 <

A 2μF capacitor is charged to 100 volt  and then its plates are connected by a conducting wire. The heat produced is

(a) 1 J

(b) 0.1 J

(c) 0.01 J

(d) 0.001 J

Kinetic energy with the electrons are emitted from the metal surface due to photoelectric effect is:

The example of non-ohmic resistance is: