138 + Interview Questions in WAVE-THEORY-OF-LIGHT IN GENERAL AWARENESS Page 3 InterviewSolution

101.	According to wave theory, different colours of light is due toA. different wavelengths of light wavesB. different frequencies of light wavesC. different amplitudes of light wavesD. none of these
Answer» Correct Answer - A

Discussion

102.	The wave theory of light does not explainA. interferenceB. refractionC. photoelectric effectD. diffraction
Answer» Correct Answer - C

Discussion

103.	According to Huygen, undetectability of ether is due toA. zero densityB. perfect transparencyC. perfect elasticityD. all of these
Answer» Correct Answer - D

Discussion

104.	According to Huygen light is propagated in the form ofA. corpusclesB. wavesC. photonsD. electrons
Answer» Correct Answer - B

Discussion

105.	Wave theory of light was proposed by Huygen inA. 1675B. 1678C. 1900D. 1987
Answer» Correct Answer - B

Discussion

106.	To explain nature of light, Huygen proposedA. Corpuscular theory of lightB. wave theory of lightC. classical theory of lightD. quantum theory of light
Answer» Correct Answer - B

Discussion

107.	The different sizes and masses of the corpuscles is responsible forA. colour of lightB. frequency of lightC. velocity of lightD. intensity of light
Answer» Correct Answer - A

Discussion

108.	Light appears to travel in straight lines sinceA. it consists of small particlesB. the velocity of light is very largeC. wavelength of light is very smallD. light is reflected by surroundings
Answer» Correct Answer - B

Discussion

109.	Which is a negative crystal from the following ?A. QuartzB. IceC. CalciteD. Polaroids
Answer» Correct Answer - C

Discussion

110.	Dichroism is the property whhereA. unequal absorption of ordinary extraordinary raysB. equal absorption of ordinary extraordinary raysC. rotating the plane of polarisationD. no change in the brightness
Answer» Correct Answer - A

Discussion

111.	The property of absorbing O-light and E-light unequally is called asA. dichroismB. resistanceC. reflectionD. double refraction
Answer» Correct Answer - A

Discussion

112.	In Nicol Prism Canada balsam acts as an………medium for the extra ordinary rayA. optically rarerB. optically denserC. opaqueD. none of these
Answer» Correct Answer - A

Discussion

113.	Polarisation of light proves the -A. light is a longitudinal waveB. light is a transverse waveC. light is not a waveD. light travels with the velocity of `3xx10^(8)ms^(-1)`
Answer» Correct Answer - B The polarisation is the property of electromagnetic waves such as light which describes the direction of their transverse electric field.

Discussion

114.	The wavelength and frequency of beam of light in water of R.I. 4/3 having wavelength 0.48 micron in air areA. `0.16 xx 10^(-6) m, 6.25 xx 10^(14) Hz`B. `0.36 xx 10^(-6) m, 6.25 xx 10^(14) Hz`C. `0.36 xx 10^(-6) m, 3.25 xx 10^(14) Hz`D. `0.26 xx 10^(-6) m, 6.25 xx 10^(14) Hz`
Answer» Correct Answer - B `lambda_(w) = (lambda_(a))/(mu) = (0.48)/(4//3) = (0.48 xx 3)/(4) = 0.36 mu m` `n = (v_(a))/(lambda_(a)) = (3 xx 10^(8))/(0.48 xx 10^(-6)) = 6.25 xx 10^(14) Hz`

Discussion

115.	The spectral line for a given element in the light received from a distant star is shifted towards longer wavelength side by `0.032%`. Deduce the velocity of star in the line of sight.A. `9.6xx10^(4)ms^(-1)`B. `11.6xx10^(-4)ms^(-1)`C. `12.6xx10^(-4)ms^(-1)`D. None of these
Answer» Correct Answer - A Here, `(Deltalamda)/lamda=(0.032)/(100)` (position, as the shift is towards longer wavelength) Now, Doppler shift is given by, `Deltalamda=-v/clamda` `v=-(Deltalamda)/lamdac=-(0.032)/(100)xx3xx10^(8)=-9.6xx10^(4)ms^(-1)` The negative sign indicates that the star is receding.

Discussion

116.	The polariser and analyser are inclined to each other at `60^(@)`. The intensity of polarised light emerging from polariser is I. The intensity of the unpolarised light incident on the polariser isA. IB. 8IC. 4ID. 2I
Answer» Correct Answer - B `I = (I_(0))/(2) cos^(2) theta = (I_(0))/(2) cos^(2) 60 = (I_(0))/(2) xx (1)/(4)` `:. I_(0) = 8 I`

Discussion

117.	An astronaut is approacing the moon. He sends a radio wave of frequency `5 xx 10^(9) Hz` towards the moon. The frequency of the radio echo received by him has a frequency `9 xx 10^(4) Hz` more than that of real frequency. The relative velocity of the rocket with respect to the moon isA. 1.35 km/sB. 2.70 km/sC. 4.05 km/sD. 5.40 km/s
Answer» Correct Answer - D `n = 5 xx 10^(9)Hz, Delta n = 9 xx 10^(4) Hz` `c = 3 xx 10^(8) m//s, v = ?` `(Delta n)/(n) = (v)/(c)` `:. v = (Delta n xx c)/(n)` `= (9 xx 10^(4) xx 3 xx 10^(8))/(5 xx 10^(9))` `v = 5.4 xx 10^(3) m//s = 5.4 km//s`

Discussion

118.	The refractive indices of alcohol and glass are 1.35 and 1.5 respectively. The refractive index of glass with respect to alcohol isA. 1.11B. 2.22C. 0.11D. 3.11
Answer» Correct Answer - A `._(a1)mu_(g) = (mu_(g))/(mu_(a1)) = (1.5)/(1.33)` `= 1.11`

Discussion

119.	When an unpolarized light of intensity `I_(0)` is incident on a polarizing sheet, the intensity of the light which does not get transmitted isA. `1/2I_(0)`B. `1/4I_(0)`C. zeroD. `I_(0)`
Answer» Correct Answer - A `l=l_(0)cos^(2)theta` Intensity of polarised light = `l_(0)/2` `therefore` Intensity of untrabsmitted light = `l_(0)-l_(0)/2=l_(0)/2`

Discussion

120.	Two polaroid sheets are placed one over the other with their axes inclied to each other at an angle `theta` . If only `12.5%` of the intensity of the light incident on the first sheet emerges out from the second sheet, the value of `theta` isA. `30^(@)`B. `60^(@)`C. `45^(@)`D. `90^(@)`
Answer» Correct Answer - B `I = (I_(0))/(2) cos^(2) theta` `(I)/(I_(0)) = (1)/(2) cos^(2) theta :. 12.5% = (1)/(2) cos^(2) theta` `cos^(2) theta = 0.25 = (1)/(4) :. cos theta = 0.25 = (1)/(2)` `:. theta = 60^(@)`

Discussion

121.	A glass plate is to be used as a polariser. If the refractive index of glass is 1.54, then the angle of polarisation for it isA. `30^(@)`B. `40^(@)`C. `57^(@)`D. `60^(@)`
Answer» Correct Answer - C `mu = tan theta_(P)` `:. theta_(P) = tan^(-1)(1.54) = 57^(@)`

Discussion

122.	A polariser in used toA. reduce intensity of lightB. increase intensity of lightC. produce polarised lightD. none of these
Answer» Correct Answer - C

Discussion

123.	For which of the following colour, refractive index is least ?A. violetB. redC. greenD. organe
Answer» Correct Answer - B

Discussion

124.	Refractive index of a medium is inversely proportional toA. colour of lightB. speed of lightC. temperatureD. all of these
Answer» Correct Answer - D

Discussion

125.	State the factors on which refractive index of a medium depend ?A. nature of pair of mediumB. wave length or speed of lightC. temperature or speed of lightD. all of these
Answer» Correct Answer - D

Discussion

126.	Two polarising sheets are placed with their planes parallel, so that light intensity transmitted is max. Through what angle must either sheet be turned so that light intensity drops to half the maximum value ?A. `60^(@), 120^(@)`B. `45^(@), 135^(@)`C. `30^(@), 150^(@)`D. `0^(@), 180^(@)`
Answer» Correct Answer - D `I = (I_(0))/(2) cos^(2) theta` `(I_(0))/(2) cos^(2) theta :. cos^(2) = 1` `theta = 0` or `180^(@)`

Discussion

127.	If the polarising angle for a given medium is ` 60^@`, then the refractive index of the medium isA. `(1)/(sqrt(3))`B. 1C. `(sqrt(3))/(2)`D. `sqrt(3)`
Answer» Correct Answer - D `theta_(P) = 60^(@), mu_(m) = ?` `mu_(m) = tan theta_(P)` `= tan 60^(@) = sqrt(3)`

Discussion

128.	If a glass plate refractive index is 1.732 is to be used as a polariser, what would be the angle of refraction?A. `30^(@)`B. `60^(@)`C. `45^(@)`D. `35^(@)`
Answer» Correct Answer - A `mu_(g)=1.732,r_(p)=?` `mu_(g)=tani_(p)` `rArr" "i_(p)=tan^(-1)(1.732)=60^(@)` `therefore" "mu_(g)=(sini_(p))/(sinr_(p))rArrsinr_(p)=(sini_(p))/(mu_(g))` `rArr" "r_(p)=sin^(-1)((sin60^(@))/(tan60^(@)))=sin^(-1)(cos60^(@))` `rArr" "r_(p)=30^(@)" "[thereforecos60^(@)=sin30^(@)]`

Discussion

129.	For which medium is refractive index maximum ?A. waterB. iceC. glassD. diamond
Answer» Correct Answer - D

Discussion

130.	The relation between the polarising angle `(i_(p))` and the refractive index (n) of the medium is given byA. `mu sin P = 1`B. `mu cot P = 1`C. `mu tan P = 1`D. `mu cos P = 1`
Answer» Correct Answer - B

Discussion

131.	The deviation produced when light wave is incident on a denser medium with an sngle of incidence equal to polarising angle is `24^@`. The angle of incidence isA. `48^(@)`B. `28.5^(@)`C. `50^(@)`D. `24^(@)`
Answer» Correct Answer - C `i-r = delta = 24` and `i+r = 90^(@)` `:. 2i = 114` `i = 57^(@)`

Discussion

132.	The angle of refraction is found to be half the angle of refraction. Then refractive index of medium isA. `2 cos^(-1) (mu//2)`B. `cos^(-1) (mu)`C. `2 sin^(-1) (mu)`D. `2 cos^(-1) (mu)`
Answer» Correct Answer - A `r = (i)/(2) " " :. i = 2r` `mu = (sin i)/(sin r) = (sin 2r)/(sin r) = (2 sin r cos r)/(sin r)` `:. cos r = (mu)/(2)` `r = cos^(-1)((mu)/(2))` `(i)/(2) = cos^(-1)((mu)/(2))` `i = 2 cos^(-1)((mu)/(2))`

Discussion

133.	A ray of light is incident on denser medium making an angle of `40^(@)` with the surface. After refraction, it is deviation by `12^(@)` from its initial path. The refractive index of denser medium will beA. `1.6`B. `1.4`C. `1.244`D. `2.4`
Answer» Correct Answer - C `delta = i-r :. r = i - delta = 50 - 12 = 38^(@)` `mu = (sin i)/(sin r) = (sin 50)/(sin 38) = (0.7660)/(0.6157) = 1.244`

Discussion

134.	When a ray of light passes from air medium to denser medium then its speed and wavelengthA. decreasesB. increasesC. remains sameD. may increase or may decrease
Answer» Correct Answer - A

Discussion

135.	The ratio of sine of angle of incidence in one medium to sine of angle of refraction in other medium isA. refractive indexB. dielectric constantC. critical angleD. dispersive power
Answer» Correct Answer - A

Discussion

136.	If a ray of light goes from a rarer medium to a denser medium, will it bend towards the normal or away from it?A. away from normalB. towards normalC. away from refracting surfaceD. none of these
Answer» Correct Answer - B

Discussion

137.	When a ray of light passes from air medium to denser medium then the refractive index isA. relative refractive indexB. absolute refractive indexC. dispersonD. none of these
Answer» Correct Answer - B

Discussion

138.	A light of wavelength 6000 A travels from rarer medium to denser medium of refractive index 1.5, If its frequncy in rarer medium is `5 xx 10^(14)` Hz, then its frequency in denser medium will beA. `3.3 xx 10^(14) Hz`B. `5 xx 10^(14) Hz`C. `2.5 xx 10^(7)m`D. `7.5 xx 10^(14) Hz`
Answer» Correct Answer - B `lambda_(a) = 6000Å, mu_(m) = 1.5 xx 10^(14) Hz, n_(d) = ?` `n_(d) = n_(a) = 5 xx 10^(14)Hz` Since due to refraction of light there is no change in frequency of light.

Discussion

Explore topic-wise InterviewSolutions in .

According to wave theory, different colours of light is due toA. different wavelengths of light wavesB. different frequencies of light wavesC. different amplitudes of light wavesD. none of these

The wave theory of light does not explainA. interferenceB. refractionC. photoelectric effectD. diffraction

According to Huygen, undetectability of ether is due toA. zero densityB. perfect transparencyC. perfect elasticityD. all of these

According to Huygen light is propagated in the form ofA. corpusclesB. wavesC. photonsD. electrons

Wave theory of light was proposed by Huygen inA. 1675B. 1678C. 1900D. 1987

To explain nature of light, Huygen proposedA. Corpuscular theory of lightB. wave theory of lightC. classical theory of lightD. quantum theory of light

The different sizes and masses of the corpuscles is responsible forA. colour of lightB. frequency of lightC. velocity of lightD. intensity of light

Light appears to travel in straight lines sinceA. it consists of small particlesB. the velocity of light is very largeC. wavelength of light is very smallD. light is reflected by surroundings

Which is a negative crystal from the following ?A. QuartzB. IceC. CalciteD. Polaroids

Dichroism is the property whhereA. unequal absorption of ordinary extraordinary raysB. equal absorption of ordinary extraordinary raysC. rotating the plane of polarisationD. no change in the brightness

The property of absorbing O-light and E-light unequally is called asA. dichroismB. resistanceC. reflectionD. double refraction

In Nicol Prism Canada balsam acts as an………medium for the extra ordinary rayA. optically rarerB. optically denserC. opaqueD. none of these

Polarisation of light proves the -A. light is a longitudinal waveB. light is a transverse waveC. light is not a waveD. light travels with the velocity of `3xx10^(8)ms^(-1)`

The wavelength and frequency of beam of light in water of R.I. 4/3 having wavelength 0.48 micron in air areA. `0.16 xx 10^(-6) m, 6.25 xx 10^(14) Hz`B. `0.36 xx 10^(-6) m, 6.25 xx 10^(14) Hz`C. `0.36 xx 10^(-6) m, 3.25 xx 10^(14) Hz`D. `0.26 xx 10^(-6) m, 6.25 xx 10^(14) Hz`

The spectral line for a given element in the light received from a distant star is shifted towards longer wavelength side by `0.032%`. Deduce the velocity of star in the line of sight.A. `9.6xx10^(4)ms^(-1)`B. `11.6xx10^(-4)ms^(-1)`C. `12.6xx10^(-4)ms^(-1)`D. None of these

The polariser and analyser are inclined to each other at `60^(@)`. The intensity of polarised light emerging from polariser is I. The intensity of the unpolarised light incident on the polariser isA. IB. 8IC. 4ID. 2I

The refractive indices of alcohol and glass are 1.35 and 1.5 respectively. The refractive index of glass with respect to alcohol isA. 1.11B. 2.22C. 0.11D. 3.11

When an unpolarized light of intensity `I_(0)` is incident on a polarizing sheet, the intensity of the light which does not get transmitted isA. `1/2I_(0)`B. `1/4I_(0)`C. zeroD. `I_(0)`

Two polaroid sheets are placed one over the other with their axes inclied to each other at an angle `theta` . If only `12.5%` of the intensity of the light incident on the first sheet emerges out from the second sheet, the value of `theta` isA. `30^(@)`B. `60^(@)`C. `45^(@)`D. `90^(@)`

A glass plate is to be used as a polariser. If the refractive index of glass is 1.54, then the angle of polarisation for it isA. `30^(@)`B. `40^(@)`C. `57^(@)`D. `60^(@)`

A polariser in used toA. reduce intensity of lightB. increase intensity of lightC. produce polarised lightD. none of these

For which of the following colour, refractive index is least ?A. violetB. redC. greenD. organe

Refractive index of a medium is inversely proportional toA. colour of lightB. speed of lightC. temperatureD. all of these

State the factors on which refractive index of a medium depend ?A. nature of pair of mediumB. wave length or speed of lightC. temperature or speed of lightD. all of these

Two polarising sheets are placed with their planes parallel, so that light intensity transmitted is max. Through what angle must either sheet be turned so that light intensity drops to half the maximum value ?A. `60^(@), 120^(@)`B. `45^(@), 135^(@)`C. `30^(@), 150^(@)`D. `0^(@), 180^(@)`

If the polarising angle for a given medium is ` 60^@`, then the refractive index of the medium isA. `(1)/(sqrt(3))`B. 1C. `(sqrt(3))/(2)`D. `sqrt(3)`

If a glass plate refractive index is 1.732 is to be used as a polariser, what would be the angle of refraction?A. `30^(@)`B. `60^(@)`C. `45^(@)`D. `35^(@)`

For which medium is refractive index maximum ?A. waterB. iceC. glassD. diamond

The relation between the polarising angle `(i_(p))` and the refractive index (n) of the medium is given byA. `mu sin P = 1`B. `mu cot P = 1`C. `mu tan P = 1`D. `mu cos P = 1`

The deviation produced when light wave is incident on a denser medium with an sngle of incidence equal to polarising angle is `24^@`. The angle of incidence isA. `48^(@)`B. `28.5^(@)`C. `50^(@)`D. `24^(@)`

The angle of refraction is found to be half the angle of refraction. Then refractive index of medium isA. `2 cos^(-1) (mu//2)`B. `cos^(-1) (mu)`C. `2 sin^(-1) (mu)`D. `2 cos^(-1) (mu)`

A ray of light is incident on denser medium making an angle of `40^(@)` with the surface. After refraction, it is deviation by `12^(@)` from its initial path. The refractive index of denser medium will beA. `1.6`B. `1.4`C. `1.244`D. `2.4`

When a ray of light passes from air medium to denser medium then its speed and wavelengthA. decreasesB. increasesC. remains sameD. may increase or may decrease

The ratio of sine of angle of incidence in one medium to sine of angle of refraction in other medium isA. refractive indexB. dielectric constantC. critical angleD. dispersive power

If a ray of light goes from a rarer medium to a denser medium, will it bend towards the normal or away from it?A. away from normalB. towards normalC. away from refracting surfaceD. none of these

When a ray of light passes from air medium to denser medium then the refractive index isA. relative refractive indexB. absolute refractive indexC. dispersonD. none of these

A light of wavelength 6000 A travels from rarer medium to denser medium of refractive index 1.5, If its frequncy in rarer medium is `5 xx 10^(14)` Hz, then its frequency in denser medium will beA. `3.3 xx 10^(14) Hz`B. `5 xx 10^(14) Hz`C. `2.5 xx 10^(7)m`D. `7.5 xx 10^(14) Hz`