physics

Question

An object located 40 cm in front of a mirror produces an erect image 20 cm from the mirror.

a) What is the radius of curvature for the mirror?

b) What type of mirror is it? 

Answer 1

(b)

Distance of image d_image = 20cm

Focal length f = 13.33

Radius of Curvature 2f = 26.66 cm    (From (a))

The distance of image lies between focal length and radius of curvature ( 2f < d_image < f) then the image is real, inverted and magnified.

 

Properties of Concave mirrors

a) A virtual & upright image occurs if the object is located between focal point and mirror.

   Image is larger than object.

b) A real image (same size) occurs if the object is located at Centre of curvature.

c) A real & inverted image occurs if the object is located between focus and Centre of curvature.

   Image is larger than the object.

d) No Image will be formed if the object is located at focal point.

 

when distance of image lies between focal length and radius of curvature then it is real, inverted and Maginified.

So the mirror is Concave mirror.

Answer 2

(a)

Object distance d_object = 76 cm

Image distance d_image = 20 cm

Formula for convex mirror is

f = 13.33 cm

Radius of Curvature C = 2f = 2*13.33 = 26.66 cm

Therefore radius of curvature is 26.66 cm.