Question

a cube of 20 cm is placed in front of a concave mirror of focal length 20 cm with its face at A at a distance of 80 cm and face B at a distance of 100 cm from mirror.​

Answer 1

Answer:

Using the mirror equation,

f

1

=

u

1

+

f

v

,

For point A,

v

A

1

=−1+

3

1

=−

3

2

.

So, v

A

=−

2

3

=−1.5

Similarly for point B,

v

B

1

=−1+

5

1

=−

5

4

.

So, v

A

=−

4

5

=−1.25.

the distance between two points is then 1.5−1.25=0.25 m

Now, using the magnification relation,

Object height

Image height

=−

Object distance

Image distance

.

For point A, Imageheight=−2×

−3

−1.5

=−1 m

And for point B, Imageheight=−2×

−5

−1.25

=−0.5 m