Question

If a candle of length 10 cm is placed 2m away from the front of a plane mirror.find the length of the image of candle and distance of the image from the candle

Answer 1

the length of the image of candle is 10cm and distance of image from the candle is 4cm because in plane mirror height of image is equal to height of object and distance from the mirror to the object is equal to the distance from the mirror to the image

Answer 2

Answer:

as the image formed by convex mirror and by the plane mirror coincide the image distance formed by the convex mirror is 4

because , distance of image from plane mirror is 12 and the distance between plane mirror and convex mirror is 8 hence 12−8=4

let f be the focal lenght of the mirror ,

u=−20 ; v=+4

v

1

+

u

1

=

f

1

4

1

−

20

1

=

f

1

f=5

hence the focal lenght is 5cm