Question

A candle is placed at a distance of 4 cm from of a concave mirror with a focal length of 12 cm. The candle is 10 cm tall.
a. Where is the image located?
b. What is the height of the image?

Answer 1

Answer:

a. 60 cm.

Explanation:

Focal length of a concave mirror f=12cm

Object length h=4

Real image length h

′

=1cm

We know that,

m=−

u

v

=

−f−(u)

−f

−

u

1

=

−12−u

−12

12+u=−48

u=−48−12

u=−60cm

Hence, the object distance is 60 cm.

Answers :

b. 5cm

Step - by - step - explanation:

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