Optics ( Part 2 ) - TRB Physics Study Materials

SI NO.	QUESTIONS		ANSWERS
26	The most common optically active substance is?		Sugar
27	When a drop of water placed between glass plate and plane convex lens in Newton’s rings system, the ring system?		Contracts
28.	In Newton’s rings experiment the diameter of certain order of dark ring is double that of second ring. The order is?		n=8
29.	The deviation from the actual size, shape and position of image as calculated theoretically is known as?		Aberration
30.	The spherical aberration produced by a  convex lens is?		+ve
31.	The ability to distinguish any two wavelength having least difference is called?		Resolving power
32.	The removal of chromatic aberration is known as?		Achromatism
33.	The resolving power increases with the?		Order of spectrum
34.	A lens free from chromatic aberration is called?		Achromatic
35.	The rays of an object point not situated on the axis of the lens, is called?		Coma
36.	A lens aberration in which the image formed by an object point is off the principle axis is?		Astigmatism
37.	The principle behind the transmission of light wave in an optical fiber is?		Total internal reflection
38.	The combination of convex lens and concave lens is called?		An astigmatism
39.	The reflective  index for air is?		1.50
40.	The angle is known as?		Angle of acceptance
41.		The glass fiber is made up of?	Metal oxide and silica glasses
42.		The optical fiber can pass the telephone signals nearly?	15000
43.		In a fiber, if only one mode is transmitted that is?	Single mode fiber
44.		The amount of light rays that can be accepted by the fiber is called?	Numerical aperture
45.		A block of ice is floating on water contained in beaker, when all the ice melts the level of water?	Remains unchanged
46.		Two lenses in contact form an achromatic doublet, their focal lengths are in the ratio 2:3 then their dispersive power is?	2:3
47.		Light transmitted by a nicol crystal is?	Plane polarized
48.		A monochromatic light of wavelength 500 nm illuminates a pair of slits 1 mm apart, on a screen 2 m away the interference fringe width is?	1.00mm
49.		A stone is dropped into a well 50m deep. It the velocity of sound in air is 332 m/s the sound will be heard after/	0.334sec
50.		Band spectrum is obtained whenever the incandescent vapoun of the excited substance are in their?	Molecular state