Two convex lenses with focal lengths 10.0 cm and 20.0 cm are separated by 70.0 cm. An object is located at 15.0 cm to the left of the first lens. Use the equation to calculate q1, P2, q2, M1 and M2 as measured from the second lens, then describe the final image?

Explanation:

Let us consider image formation from first mirror

object distance u = - 15 cm

v = ?

f = 10 cm

1 / v - 1 / u = 1 / f

1 / v + 1 / 15 = 1 / 10

1 / v = 1 / 10 - 1 / 15

= .1 - .067

= .033

v = 30 cm

Magnification M1 = v / u = - 30 / 15 = - 2

This image will act as object for second mirror

object distance for second mirror

u = 70 - 30 = 40 cm

f = 20 cm

v = ?

1 / v - 1 / u = 1 / f

1 / v + 1 / 40 = 1 / 20

1 / v = 1 / 20 - 1 / 40

= .05 - .025

= .025

v = 40 cm

Magnification M2 = v / u

= - 40 / 40

= -1 .

overall magnification

M = M1 X M2

= -2 x -1

= + 2

Final image will be 2 times the object and it will be real and it will be erect with respect to object .