For which one of the following, Bohr model is not
valid ?
(1) Hydrogen atom
(2) Singly ionised helium atom (He+)
(3) Deuteron atom
(4) Singly ionised neon atom (Ne+)

The ratio of contributions made by the electric field
and magnetic field components to the intensity of
an electromagnetic wave is : (c=speed of
electromagnetic waves)
(1) c : 1
(2) 1 : 1
(3) 1 : c
(4) 1 : c2

The Brewsters angle i
b
for an interface should be :
(1) 0° < i_b < 30°
(2) 30° < i_b < 45°
(3) 45° < i_b < 90°
(4) i_b = 90°

A cylinder contains hydrogen gas at pressure of
249 kPa and temperature 27°C.
Its density is : (R=8.3 J mol-1 K-1)
(1) 0.5 kg/m3
(2) 0.2 kg/m3
(3) 0.1 kg/m3
(4) 0.02 kg/m3

A ray is incident at an angle of incidence i on one
surface of a small angle prism (with angle of prism
A) and emerges normally from the opposite surface.
If the refractive index of the material of the prism
is µ, then the angle of incidence is nearly equal
to :
(1)
``\frac{A}{2µ}``
(2) ``\frac{2A}{µ}``
(3) µA
(4)``\frac{µA}{2}``

Two cylinders A and B of equal capacity are
connected to each other via a stop cock. A contains
an ideal gas at standard temperature and pressure.
B is completely evacuated. The entire system is
thermally insulated. The stop cock is suddenly
opened. The process is :
(1) isothermal
(2) adiabatic
(3) isochoric
(4) isobaric

The energy equivalent of 0.5 g of a substance is :
(1) ``4.5 ×10^{16} J``
(2) ``4.5 ×10^{13} J``
(3) ``1.5 ×10^{13} J``
(4) ``0.5 ×10^{13} J``

A body weighs 72 N on the surface of the earth.
What is the gravitational force on it, at a height
equal to half the radius of the earth ?
(1) 48 N
(2) 32 N
(3) 30 N
(4) 24 N

The solids which have the negative temperature
coefficient of resistance are :
(1) metals
(2) insulators only
(3) semiconductors only
(4) insulators and semiconductors

The phase difference between displacement and
acceleration of a particle in a simple harmonic
motion is :
(1) π rad
(2) ``\frac32``π rad;
(3) ``\frac{\pi}{2}``rad
(4) zero

A screw gauge has least count of 0.01 mm and
there are 50 divisions in its circular scale.
The pitch of the screw gauge is :
(1) 0.01 mm
(2) 0.25 mm
(3) 0.5 mm
(4) 1.0 mm

In a guitar, two strings A and B made of same
material are slightly out of tune and produce beats
of frequency 6 Hz. When tension in B is slightly
decreased, the beat frequency increases to 7 Hz.
If the frequency of A is 530 Hz, the original
frequency of B will be :
(1) 523 Hz
(2) 524 Hz
(3) 536 Hz
(4) 537 Hz

Two particles of mass 5 kg and 10 kg respectively
are attached to the two ends of a rigid rod of length
1 m with negligible mass.
The centre of mass of the system from the 5 kg
particle is nearly at a distance of :
(1) 33 cm
(2) 50 cm
(3) 67 cm
(4) 80 cm

Find the torque about the origin when a force of
``3\hat{j}N`` acts on a particle whose position vector is
``2 \hat{k}`` m
(1) ``6\hat{i} N m ``
(2) ``6\hat{j} N m``
(3) ``-6\hat{i} N m``
(4) ``6\hat{k} N m``