Practice Test


1) The dispersive power of the material of prism is given by


2) A white ray of light is passing through a parallel glass slab. The emergent ray


3) We use flint glass prism to disperse polychromatic light because lights of different colours


4) Dispersive power depends upon


5) A sunrise or sunset, the sun looks more red than at midday because


6) A prism CANNOT be used


7) Refractive index is


8) The dispersive power is maximum for the material


9) Refractive index, frequency and deviation are maximum for


10) Light is dispersed by a prism because


11) White light is incident on thin-walled hollow glass prism. The emergent light is


12) In deviation without dispersion,


13) When a prism is placed in the position of minimum deviation, the ray of light within the prism


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


15) 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


16) A convex lens, a glass prism and a solid sphere all are made of the same glass. The dispersive power will be


17) The angle of minimum deviation of a flint glass prism relative to crown, glass prism having the same angle of refraction for the same wavelength will be


18) In a direct vision spectroscope, one uses a flint and a crown glass prism combination to get zero mean deviation but a finite dispersion. Which of the following is an acceptable diagrammatic representation ?
[ C = crown, F = flint, V = violet, R = red ]


19) Which of the following diagrams shows correctly the dispersion of white light by a prism ?


20) A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and the latter is equal to 1 / 2 of the angle of prism. The angle of deviation is


21) If the refractive indices of crown glass fro red, yellow and violet colours are 1.5140, 1.5270 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 glasses are respectively


22) The angle of deviation is the angle between


23) Statement 1 : A beam of white light does not give a spectrum on passing through a hollow prism.
Statement 2 : Speed of light outside the prism is different from the speed of light inside the prism


24) Statement 1 : If the angles of the base of the prism are equal, then in the position of minimum deviation, the refracted ray will pass parallel to the base of the prism.
Statement 2 : In the case of minimum deviation, the angle of incidence is equal to the angle of emergence


25) The angle of incidence is


26) What is the angular width of the spectrum


27) What is the length of spectrum if it is focussed on a screen by a lens of focal length 100 cm ?


28) Statement 1 : It is possible to eliminate dispersion by combining two prism of same refracting angles but of different materials.
Statement 2 : The angular dispersion depends on refractive index of the material of the prism.


29) Statement 1 : Dispersion of light occurs between velocity of light in a material depends upon its colour.
Statement 2 : The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism


30) An experiment was performed based on the above theory with red, green and blue light. Their refractive indices in the material were 1.39, 1.44 and 1.47 respectively. Which colour would get separated ?


31) If hypothetically the density of the material is increased gradually, then which of the colour gets separated next ?


32) As the density of the material of the prism keeps on increasing, then which of the following statement holds good ?


33) Which source is associated with a line emission spectrum


34) When white light passes through a glass prism, one gets spectrum on the other side of the prism. In the emergent beam, the ray which is deviating least is or Deviation by a prism is lowest for


35) Fraunhofer lines are obtained in


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


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


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


39) The number of wavelengths in the visible spectrum


40) The black lines in the solar spectrum during solar eclipse can be explained by


41) 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


42) The spectrum of light emitted by a glowing solid is


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


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


45) Our eye is most sensitive for which of the following wavelength


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


47) Band spectrum is obtained when the source emitting light is in the form of or Band spectrum is characteristic of


48) 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


49) The fine powder of a coloured glass is seen as


50) When a white light passes through a hollow prism, then


51) In dispersion without deviation


52) 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


53) Band spectrum is produced by


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


55) Line spectrum was first of all theoretically explained by


56) The spectrum of iodine gas under white light will be


57) Continuous spectrum is not due to


58) Fraunhofer lines are produced by


59) A medium is said to be dispersive, if


60) Dispersion can take place for


61) 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


62) The true statement is


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


64) When light emitted by a white hot solid is passed through a sodium flame, the spectrum of the emergent light will show


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


66) 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


67) When seen in green light, the saffron and green portions of our National Flag will appear to be


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


69) Line spectrum contains information about


70) Missing lines in a continuous spectrum reveal


71) A neon sign does not produce


72) The refractive index of flint glass for blue F line is 1.6333 and red C line is 1.6161. If the refractive index for yellow D line is 1.622, the dispersive power of the glass is


73) The wavelength of emission line spectrum and absorption line spectrum of a substance are related as


74) From which source a continuous emission spectrum and a line absorption spectrum are simultaneously obtained


75) The splitting of white light into several colours on passing through a glass prism is due to


76) A white screen illuminated by green and red light appears to be


77) Dark lines on solar spectrum are due to


78) Line spectra are due to


79) The path of a refracted ray of light in a prism is parallel to the base of the prism only when the


80) For a medium, refractive indices for violet, red and yellow are 1.62, 1.52 and 1.55 respectively, then dispersive power of medium will be


81) If refractive index of red, violet and yellow lights are 1.42, 1.62 and 1.50 respectively for a medium. Its dispersive power will be


82) Fraunhofer spectrum is a


83) Colour of the sky is blue due to


84) Which of the following spectrum have all the frequencies from high to low frequency range


85) Stars are not visible in the day time because


86) Which of the following colours suffers maximum deviation in a prism?


87) The refractive index of the material of the prism for violet colour is 1.69 and that for red is 1.65. If the refractive index for mean colour is 1.66, the dispersive power of the material of the prism


88) Dispersion of light is due to


89) Which of the prism is used to see infrared spectrum of light


90) When white light enters a prism, it gets split into its constituent colours. This is due to


91) The dispersive powers of crown and flint glasses are 0.02 and 0.04 respectively. In an achromatic combination of lenses the focal length of flint glass lens is 40 cm. The focal length of crown glass lens will be


92) When a ray of light is incident normally on one refracting surface of an equilateral prism (Refractive index of the material of the prism = 1.5


93) Consider the following two statements A and B and identify the correct choice in the given answers:
A : Line spectra is due to atoms in gaseous state,
B : Band spectra is due to molecules


94) The nature of sun's spectrum is


95) For a prism of refractive index 1.732, the angle of minimum deviation is equal to the angle of the prism. The angle of the prism is


96) The spectrum obtained from an electric lamp or red hot heater is


97) Which one of the following alternative is FALSE for a prism placed in a position of minimum deviation


98) The solar spectrum during a complete solar eclipse is


99) Why sun has elliptical shape on the time when rising and sun setting? It is due to


100) In the formation of a rainbow light from the sun on water droplets undergoes


101) The Cauchy's dispersion formula is


102) A convex lens, a glass slab, a glass prism and a solid sphere all are made of the same glass, the dispersive power will be


103) A parallel beam of white light falls on a convex lens. Images of blue, yellow and red light are formed on other side of the lens at a distance of 0.20 m, 0.205 m and 0.214 m respectively. The dispersive power of the material of the lens will be


104) The refractive index of the material of the prism for violet colour is 1.69 and that for red is 1.65. If the refractive index for mean colour is 1.66, the dispersive power of the material of the prism


105) The refractive index of a particular material is 1.67 for blue light, 1.65 for yellow light and 1.63 for red light. The dispersive power of the material is


106) A beam of light composed of red and green ray is incident obliquely at a point on the face of rectangular glass slab. When coming out on the opposite parallel face, the red and green ray emerge from


107) White light is passed through a prism ........... colour shows minimum deviation