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IITIANS PACE

1. Two blocks each of mass m lie on a smooth table. They are attached to two

other masses as shown in the figure. The pulleys and strings are light. An

object O is kept at rest on the table. The sides AB & CD of the two blocks are

made reflecting. The acceleration of two images formed in those two reflecting

surfaces w.r.t. each other is:

(A) 5g / 6 (B) 5g / 3 (C) g / 3 (D) 17g / 6

2. In the diagram shown, all the velocities are given with respect to earth. What is

the relative velocity of the image in mirror (1) with respect to the image in the

mirror (2)? The mirror (1) forms an angle b with the vertical.

(A) 2Vsin2b (B) 2Vsinb (C) 2V / sin2b (D) none

QUIZ

Prof. SSpRay Optics-Quiz : 1

Score : ________ / 40

SAMCQ ( 3 , -1 X 10 = 30 )

3. An unnumbered wall clock shows time 04: 25: 37, where 1st term represents hours, 2nd

represents minutes & the last term represents seconds. What time will its image in a plane

mirror show.

(A) 08: 35: 23 (B) 07: 35: 23 (C) 07: 34: 23 (D) none of these

4. Two mirrors are inclined at an angle qas shown in the figure. Light ray is incident

parallel to one of the mirrors. The ray will start retracing its path after third

reflection if :

(A)q= 45 (B) q= 30 (C)q = 60 (D) all three

5. A plane mirror is moving with velocity k8j5i4 ++ . A point object in f ront of

the mirror moves with a velocity k5j4i3 ++ . Here k is along the normal to the plane mirror

and facing towards the object. The velocity of the image is:

(A) k5j4i3 +-- (B) k11j4i3 ++ (C) k11j4i3 +-- (D) k11j9i7 ++

6. A point object is kept in front of a plane mirror. The plane mirror is doing SHM of amplitude 2 cm.

The plane mirror moves along the x-axis and x- axis is normal to the mirror. The amplitude of themirror is such that the object is always infront of the mirror. The amplitude of SHM of the image is

(A) zero (B) 2 cm (C) 4 cm (D) 1 cm

7. A person s eye level is 1.5 m. He stands in front of a 0.3m long plane mirror which is 0.8 m above

the ground. The length of the image he sees of himself is:

(A) 1.5m (B) 1.0m (C) 0.8m (D) 0.6m

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IITIANS PACE

9. Images of an object placed between two plane mirrors whose reflecting surfaces make an angle of

900

with one another lie on a :(A) straight line (B) zig-zag curve (C) circle (D) ellipse

10. Two plane mirrors are parallel to each other and spaced 20 cm apart. An object is kept in

between them at 15 cm from A. Out of the following at which point(s) image(s) is/are not

formed in mirror A (distance measured from mirror A):

(A) 15 cm (B) 25 cm (C) 45 cm (D) 55 cm

FILL IN THE BLANKS ( 3 , 3 , 4 = 10 )

8. A person is standing in a room of width 200 cm. A plane square mirror of length 10 cm is fixed

on a wall in front of the person. The person looks into the mirror from distance 50 cm. How

much width (height) of the wall behind him will he be able to see:

(A) 30 cm (B) 40 cm (C) 50 cm (D) none of these

11. Two plane mirrors are inclined at an angle 70. A ray incident on one mirror at angleqafter reflection

falls on the second mirror and is reflected from there parallel to the first mirror. qis

____________

12. A point object is 10 cm away from a plane mirror while the eye of an observer (pupil diameter

5.0 mm) is 20 cm away. Assuming both the eye and point to be on the same line perpendicular to the

mirror, the area of the mirror used in observing the reflection of the point is

____________

13. A light ray I is incident on a plane mirror M. The mirror is rotated in the

direction as shown in the figure by an arrow at frequencyp

9rev/sec.

The light reflected by the mirror is received on the wall W at a distance

10 m from the axis of rotation. When the angle of incidence becomes

37 find the speed of the spot (a point) on the wall?

_______________

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