Question

Two spherical mirrors (convex and concave) having the same focal length of o 1 m 36 cm are arranged so that their optical axes coincide. The separation between the mirrors is 1 m. At what distance from the concave mirror should an object be placed so that its images formed by the concave and convex mirror independently are identical in size

Answer 1

Dear Students,

◆ Answer -

u = 86 cm

● Explanation -

Let the object be placed at distance u from the concave mirror.

Magnification by concave mirror will be -

M = -f / (u-f)

Magnification by convex mirror will be -

M = -f / (L-u+f)

Equating two equations,

-f / (u-f) = -f / (L-u+f)

u - f = L - u + f

2u = L + 2f

2u = 100 + 2×36

2u = 172

u = 172/2

u = 86 cm

Therefore, object should be placed at distance of 86 cm from the concave mirror.

Thanks for asking.