Physics M.C.Q (1 Marks)

A neon sign does not produce

(a) Line spectrum	(b) An emission spectrum
(c) An absorption spectrum	(d) Photons

What will be the colour of sky as seen from the earth, if there were no atmosphere

(a) Black

(b) Blue

(c) Orange

(d) Red

The true statement is

(a) The order of colours in the primary and the secondary rainbows is the same

(b) The intensity of colours in the primary and the secondary rainbows is the same

(c) The intensity of light in the primary rainbow is greater and the order of colours is the same than the secondary rainbow

(d) The intensity of light for different colours in primary rainbow is greater and the order of colours is reverse than the secondary rainbow

A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is

(a) 45°

(b) 39°

(c) 20°

(d) 30°

Dispersion can take place for

(a) Transverse waves only but not for longitudinal waves

(b) Longitudinal waves only but not for transverse waves

(c) Both transverse and longitudinal waves

(d) Neither transverse nor longitudinal waves

A ray of light is incident at an angle of 60° on one face of a prism of angle 30°. The ray emerging out of the prism makes an angle of 30° with the incident ray. The emergent ray is

(a) Normal to the face through which it emerges

(b) Inclined at 30° to the face through which it emerges

(c) Inclined at 60° to the face through which it emerges

(d) None of these

A medium is said to be dispersive, if

(a) Light of different wavelengths propagate at different speeds

(b) Light of different wavelengths propagate at same speed but has different frequencies

(c) Light is gradually bent rather than sharply refracted at an interface between the medium and air

(d) Light is never totally internally reflected

Fraunhofer lines are produced by

(a) The element present in the photosphere of sun

(b) The elements present in the chromosphere of the sun

(c) The vapour of the element present in the chromosphere of the sun

(d) The carbon dioxide present in the atmosphere

Continuous spectrum is not due to

(a) Hydrogen flame	(b) Electric bulb
(c) Kerosene oil lamp flame	(d) Candle flame

The spectrum of iodine gas under white light will be

(a) Only violet

(b) Bright lines

(c) Only red lines

(d) Some black bands in continuous spectrum

Line spectrum was first of all theoretically explained by

(a) Swan

(b) Fraunhofer

(c) Kirchoff

(d) Bohr

Line spectrum contains information about

(a) The atoms of the prism

(b) The atoms of the source

(c) The molecules of the source

(d) The atoms as well as molecules of the source

Emission spectrum of  gas

(a) Is a line spectrum	(b) Is a band spectrum
(c) Is a continuous spectrum	(d) Does not fall in the visible region

At sun rise or sunset, the sun looks more red than at mid-day because

(a) The sun is hottest at these times	(b) Of the scattering of light
(c) Of the effects of refraction	(d) Of the effects of diffraction

A ray of light incident normally on an isosceles right angled prism travels as shown in the figure. The least value of the refractive index of the prism must be

(a)

(b)

(c) 1.5

(d) 2.0

Angle of prism is A and its one surface is silvered. Light rays falling at an angle of incidence 2A on first surface return back through the same path after suffering reflection at second silvered surface. Refractive index of the material of prism is

(a) 2 sin A

(b) 2 cos A

(c)

(d) tan A

At the time of total solar eclipse, the spectrum of solar radiation would be

(a) A large number of dark Fraunhofer lines

(b) A less number of dark Fraunhofer lines

(c) No lines at all

(d) All Fraunhofer lines changed into brilliant colours

Deviation of 5° is observed from a prism whose angle is small and whose refractive index is 1.5. The angle of prism is

(a) 7.5°

(b) 10°

(c) 5°

(d) 3.3°

The band spectra (characteristic of molecular species) is due to emission of radiation

(a) Gaseous state

(b) Liquid state

(c) Solid state

(d) All of three states

For a material, the refractive indices for red, violet and yellow colour light are respectively 1.52, 1.64 and 1.60. The dispersive power of the material is

(a) 2

(b) 0.45

(c) 0.2

(d) 0.045

Angle of a prism is 30° and its refractive index is  and one of the surface is silvered. At what angle of incidence, a ray should be incident on one surface so that after reflection from the silvered surface, it retraces its path

(a) 30°

(b) 60°

(c) 45°

(d)

A thin prism P₁ with angle 4° and made from glass of refractive index 1.54 is combined with another thin prism P₂ made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of prism P₂ is

(a) 2.6°

(b) 3°

(c) 4°

(d) 5.33°

Minimum deviation is observed with a prism having angle of prism A, angle of deviation δ, angle of incidence i and angle of emergence e. We then have generally

(a) i > e

(b) i < e

(c) i = e

(d) i = e = δ

The minimum deviation produced by a hollow prism filled with a certain liquid is found to be 30°. The light ray is also found to be refracted at angle of 30°. The refractive index of the liquid is

(a)

(b)

(c)

(d)

If the refractive indices of a prism for red, yellow and violet colours be 1.61, 1.63 and 1.65 respectively, then the dispersive power of the prism will be

(a)

(b)

(c)

(d)

The angle of minimum deviation measured with a prism is 30° and the angle of prism is 60°. The refractive index of prism material is

(a)

(b) 2

(c) 3/2

(d) 4/3

The refractive indices of violet and red light are 1.54 and 1.52 respectively. If the angle of prism is 10°, then the angular dispersion is

(a) 0.02

(b) 0.2

(c) 3.06

(d) 30.6

Light from sodium lamp is passed through cold sodium vapours, the spectrum of transmitted light consists of

(a) A line at 5890 Å	(b) A line at 5896 Å
(c) Sodium doublet lines	(d) No spectral features

When a white light passes through a hollow prism, then

(a) There is no dispersion and no deviation	(b) Dispersion but no deviation
(c) Deviation but no dispersion	(d) There is dispersion and deviation both

The fine powder of a coloured glass is seen as

(a) Coloured	(b) White
(c) That of the glass colour	(d) Black

A circular disc of which 2/3 part is coated with yellow and 1/3 part is with blue. It is rotated about its central axis with high velocity, then it will be seen as

(a) Green

(b) Brown

(c) White

(d) Violet

In the position of minimum deviation when a ray of yellow light passes through the prism, then its angle of incidence is

(a) Less than the emergent angle

(b) Greater than the emergent angle

(c) Sum of angle of incidence and emergent angle is 90°

(d) Equal to the emergent angle

The angle of minimum deviation for a prism is 40° and the angle of the prism is 60°. The angle of incidence in this position will be

(a) 30°

(b) 60°

(c) 50°

(d) 100°

Flint glass prism is joined by a crown glass prism to produce dispersion without deviation. The refractive indices of these for mean rays are 1.602 and 1.500 respectively. Angle of prism of flint prism is 10°, then the angle of prism for crown prism will be

(a) 12°2.4'

(b) 12°4’

(c) 1.24°

(d) 12°

Band spectrum is characteristic of

(a) Atoms

(b) Molecules

(c) Plasma

(d) None of the above

The minimum temperature of a body at which it emits light is

(a) 1200°C

(b) 1000°C

(c) 500°C

(d) 200°C

If the refractive indices of crown glass for red, yellow and violet colours are 1.5140, 1.5170 and 1.5318 respectively and for flint glass these are 1.6434, 1.6499 and 1.6852 respectively, then the dispersive powers for crown and flint glass are respectively

(a) 0.034 and 0.064

(b) 0.064 and 0.034

(c) 1.00 and 0.064

(d) 0.034 and 1.0

Our eye is most sensitive for which of the following wavelength

(a) 4500 Å

(b) 5500 Å

(c) 6500 Å

(d) Equally sensitive for all wave lengths of visible spectrum

By placing the prism in minimum deviation position, images of the spectrum

(a) Becomes inverted

(b) Becomes broader

(c) Becomes distinct

(d) Becomes intensive

Which of the following element was discovered by study of Fraunhofer lines

(a) Hydrogen

(b) Oxygen

(c) Helium

(d) Ozone

The spectrum of light emitted by a glowing solid is

(a) Continuous spectrum

(b) Line spectrum

(c) Band spectrum

(d) Absorption spectrum

A parallel beam of monochromatic light is incident at one surface of a equilateral prism. Angle of incidence is 55° and angle of emergence is 46°. The angle of minimum deviation will be

(a) Less than 41°

(b) Equal to 41°

(c) More than 41°

(d) None of the above

A light ray is incident by grazing one of the face of a prism and after refraction ray does not emerge out, what should be the angle of prism while critical angle is C

(a) Equal to 2C

(b) Less than 2C

(c) More than 2C

(d) None of the above

The dispersive power is maximum for the material

(a) Flint glass

(b) Crown glass

(c) Mixture of both

(d) None of the above

The number of wavelengths in the visible spectrum

(a) 4000

(b) 6000

(c) 2000

(d) Infinite

When white light passes through the achromatic combination of prisms, then what is observed

(a) Only deviation	(b) Only dispersion
(c) Deviation and dispersion	(d) None of the above

Dispersive power depends upon

(a) The shape of prism	(b) Material of prism
(c) Angle of prism	(d) Height of the prism

In the formation of primary rainbow, the sunlight rays emerge at minimum deviation from rain-drop after

(a) One internal reflection and one refraction

(b) One internal reflection and two refractions

(c) Two internal reflections and one refraction

(d) Two internal reflections and two refractions

Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is (cos 41° = 0.75)

(a) 62°

(b) 41°

(c) 82°

(d) 31°

The focal lengths for violet, green and red light rays are  and  respectively. Which of the following is the true relationship

(a)

(b)

(c)

(d)