Question

An image by a concave mirror is 4 times greater than the object. If the radius of curvature 20 cm, determine the object distance in front of the mirror!

Answer 1

Answer:

R= (‐20 cm) ( coz concave mirror have negative focal length)

F=R/2

= ‐ 20/2

= ‐10 cm

Magnification, M= ‐v/u

=> 4= ‐ v/u

=>v= ‐4u

According to mirror's formula :

1/f= 1/u +1/v

‐1/10=1/u+(‐1/4u)

‐1/10= 1/u ‐1/4u

‐4u=40+10

u= ‐50/4

u=(tex)/frac( ‐100) (4)(/tex)

u=12.5 cm

Answer 2

An image by a concave mirror is 4 times greater than the object. If the radius of curvature 20 cm, determine the object distance in front of the mirror!