# Physics Online Test

The presence of gravitational field is required for the heat transfer by
Conduction
Stirring of liquids
Natural convection

If 1 g of steam is mixed with 1 g of ice, then the resultant temperature of the mixture is





A  rise in temperature is observed in a conductor by passing a current. When the current is doubled the rise in temperature will be approximately




A sample of gas expands from volume  to . The amount of work done by the gas is greatest, when the expansion is
Isobaric
Isothermal
Equal in all cases
A diatomic as initially at  is compressed adiabatically to one eighth of its original volume. The temperature after compression will be




An ideal Carnot engine, whose efficiency is 405, receives heat at 400 K. If its efficiency is 50% , then the intake temperature for the same exhaust temperature
600 K
700 K
800 K
900 K
A body cools from  to  in 5s. How long will it take to cool from  to  ? Assume the temperature of surroundings to be  and Newton’s law of cooling to be valid.
2.5 s
10 s
20 s
5 s
If the temperature of the sun is doubled, the rate of energy received on earth will be increased by a factor of
2
4
8
16
Which of the following is not thermo dynamical function ?
Enthalpy
Wok done
Gibb’s energy
Internal energy
110 Joules of heat is added to a gaseous system whose internal energy is 40J; then the amount of external work done is
150 J
70 J
110 J
40 J
An ideal gas A and a real gas B have their volumes increased from V to 2V under isothermal conditions. The increases in internal energy
Will be same in both A and B
Will be zero in both the gases
Of B will be more than that of A
Of A will be more than that of B
The number of transnational degrees of freedom of a diatomic gas is
2
3
5
6
Mercury thermometer can be used measure temperature up to




One mole of an ideal gas requires 207 J heat to rise the temperature by 10 K when heated at constant pressure. If the same gas is heated at constant volume to raise the temperature by the same 10 K, the heat required is Given the gas constant 
198. 7 J
29 J
215 .3 J
124 J
According to kinetic theory of gases, at absolute zero of temperature
Water freezes
Liquid helium freezes
Molecular motion stops
Liquid hydrogen freezes

The radius of curvature of a thin Plano-convex lens is 10 cm (of curved surface) and the refractive index is 1.5 . If the plane surface is silvered, then it behaves like a concave mirror of focal length
10 cm
15 cm
20 cm
5 cm
The refractive index of the material of the prism is ; then the angle of minimum deviation of the prism is




Colors appear on a thin soap film and on soap bubbles due to the phenomenon of
Refraction
Dispersion
Interference
Diffraction
A Plano-convex lens is made of material of refractive index 1.6 The radius of curvature of the curved surface is 60 cm. The focal length of the lens is
50 cm
100 cm
200 cm
400 cm
A luminous object is placed at a distance of 30 cm from the convex lens of focal length 20 cm. On the other side of the lens, at what distance from the lens a convex mirror of radius of curvature 10 cm be placed in order to have an upright image of he object coincident with it ?
12 cm
30 cm
50 cm
60 cm
An astronomical telescope has a length of 44 cm and tenfold magnification. The focal length of the objective lens is
4 cm
40 cm
44 cm
440 cm
One face of rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face, forms an image 12 cm behind the silvered face. The refractive index of the glass is
0.4
0.8
1.2
1.6
A polyatomic gas with n degrees of freedom has a mean energy per molecule given by




In a Fresnel’s Biprism experiment, the two positions of lens give separation between the slits as 16 cm and 9 cm respectively. What is the actual distance of separation?
12.5 cm
12 cm
13 cm
14 cm
If two mirrors are kept inclined at  to each other and a body is placed at the middle, then total number of images formed, is
Six
Five
Four
Three
The Hypermetropia is a
Short-sight defect
Long-sight defect
Bad vision due to old age
None of these
An achromatic combination of lenses is formed by joining
2 convex lenses
2 convex lenses
1 convex, 1 concave lens
1 convex and 1 plane mirror
Focal length of a convex lens will be maximum for
Blue light
Yellow light
Green light
Red light
A parallel beam of monochromatic light of wavelength 5000 Å is incident normally on a single narrow slit of width 0.01 mm. The light is focused by a convex lens on a screen placed in focal plane. The first minimum will be formed for the angle of diffraction equal to




Interference was observed in interference chamber where air was present, now the chamber is evacuated, and if the same light is used, a careful observed will see
No interference
Interference with brighter bands
Interference with dark bands
Interference fringe with larger width
If yellow light emitted by sodium lamp in Young’s double slit experiment is replaced by monochromatic blue of light of the same intensity
Fringe width will decreases
Fringe width will increases
Fringe width will remains unchanged
Fringes will becomes less intense
A beam of monochromatic light is refracted from vacuum into a medium of refractive index 1.5. The wavelength of refracted light will be
Dependent on intensity of refracted light
Same
Smaller
Larger
Ratio of intensities of two waves are given by 4 : 1 Then ratio of the amplitudes of the two waves is
2 : 1
1 : 2
4 : 1
1 : 4
A beam of monochromatic light is refracted from vacuum into a medium of refractive index 1.5, The of refracted light will be
Dependent on intensity of refracted light
Same
Smaller
Larger

0.30 mm
0.40 mm
0.53 mm
450 microns
Pick out the longest wavelength from the following types of radiations.
Blue light
Gamma rays
X-rays
Red light
A particle executing simple harmonic motion of amplitude 5 cm has maximum speed of 31.4 cm/s. The frequency of its oscillations is :
4 Hz
3 Hz
2 Hz
1 Hz
A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2 m and 3 m respectively from the source. The ratio of the intensities of the waves at P and Q is:
3 : 2
2 : 3
9 : 4
4 : 9
Which one of the following statements is true ?
The sound waves in air are longitudinal while the light waves are transverse
Both light and sound waves in air are longitudinal
Both light and sound waves can travel in vacuum
Both light and sound waves in air are transverse
The time of reverberation of a room A is one second. What will be the time (in seconds) of reverberation of room, having all the dimensions double of those of room A?
4
1/2
1
2
The potential energy of a long spring when stretched by 2 cm is U. If the spring is stretched by 8 cm, the potential energy stored in it is
8 U
16 U
U/4
4 U
Two sound waves with wavelengths 5.0 m and 5.5 m respectively each propagate in a gas with velocity 330 m/s. We expect the following number of beats per second.
0
1
6
12
Focal length of a convex lens of refractive index 1.5 is 2 cm. Focal length of lens when immersed in a liquid of refractive index of 1.25 will be
10 cm
2.5 cm
5 cm
7.5 cm
Which one of the following phenomena is not explained by Huygens’s construction of wave front?
Refraction
Reflection
Diffraction
Origin of spectra
Which of the following phenomenon is not common to sound and light waves?
Interference
Diffraction
Coherence
Polarization
Ray optics is valid, when characteristic dimensions are
Of the same order as the wavelength of light
Much smaller than the wavelength of light
Of the order of one millimeter
Much larger than the wavelength of light
Interference is possible in
Light waves only
Sound waves only
Both light and sound waves
Neither light nor sound waves
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paper consists of 50 questions which are required to be finished in an hours time

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