CBSE
Multiple Choice QuestionsIn a laboratory four convex lenses L1 ,L2 , L3 and L4 of focal lengths 2, 4, 6 and 8 cm,respectively are available. Two of these lenses form a telescope of length 10 cm and magnifying power 4. The objective and eye lenses are respectively
L2 , L3
L1, L4
L1 , L2
L4 , L1
The frequency of a light wave in a material is 2 x 1014 Hz and wavelength is 5000 Ao. The refractive index of material will be
1.40
1.50
3.00
1.33
Which of the following is true for rays coming from infinity?
Two images are formed
continuous image is formed between focal points of upper and lower lens
One image is formed
None of the above
The refractive index of glass is 1.520 for red light and 1.525 for blue light. Let D1 and D2 be angles of minimum deviation for red and blue light respectively in a prism of this glass. then,
D1 < D2
D1 = D2
D1 can be less than or greater than D2 depending upon the angle of prism
D1 > D2
The angular resolution of a 10 cm diameter telescope at a wavelength of 5000 A is of the order of
106 rad
10-2 rad
10-4 rad
10-6 rad
In refraction, light waves are bent on passing from one medium to the second medium, because, in the second medium
the frequency is different
the coefficient of elasticity is different
the speed is different
the amplitude is smaller
A plane mirror produces a magnification of
zero
-1
+1
between 0 and +1
A light movs from denser to rarer medium, which of the following is correct?
Energy increases
Frequency increases
Phase changes by 90°
Velocity increases
A telescope has focal length of objective and eye-piece as 200 cm and 5 cm respectively. What is magnification of telescope?
40
80
50
0.01
A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens is 4D, the power of a cut lens will be
2D
3D
4D
5D
