Question

A small statue has a height of 3.5 cm and is placed in front of a concave mirror. The image of the statue is inverted, 1.6 cm tall, and located 13 cm away from the mirror. Find the focal length of the mirror.

Answer 1

given that

object heigth = h₀= 3.5cm

image height = h_i= 1.6cm

image distance = d_i= 13cm

m = h_i/h₀

m = ----

we know that d₀ = -d_i/ m

plug in valus d₀= ------cm

from the mirror eq

1/f = 1/d₀ + 1/d_i

plug in values f = ------cm

Answer 2

f is + if the mirror is a concave mirror

Answer 3

3.5 =マ 3.5 2-394 cm

Answer 4

A concave mirror has a real focal length +f, image distance v = 13.0cm

Finding the object distance (u) from magnification ..

M = v/u = 1.6cm / 3.5cm = 0.457
u = v/M .. 13cm / 0.457 .. .. u = 28.45cm

Applying .. 1/f = 1/v + 1/u

1/f = 1/13cm + 1/28.45cm

?f = 8.9223cm