A thin convex lens of focal length 10 cm and a thin concave lens of focal length 20 cm are in contact. The combination acts as:

Question

A thin convex lens of focal length 10 cm and a thin concave lens of focal length 20 cm are in contact. The combination acts as: (A) Concave lens of focal length 10.0 cm (B) Concave lens of focal length 20.0 cm (C) Convex or concave lens depending on refractive index of material of the lens (D) None of the above

Tardigrade Admin · Accepted Answer

(1/F)=(1/f1)+(1/f2)=(1/10)-(1/20),i.,e.F=20 cm

Q. A thin convex lens of focal length 10 cm and a thin concave lens of focal length 20 cm are in contact. The combination acts as:

Concave lens of focal length 10.0 cm

Concave lens of focal length 20.0 cm

Convex or concave lens depending on refractive index of material of the lens

None of the above

$\frac{1}{F} = \frac{1}{f _{1}} + \frac{1}{f _{2}} = \frac{1}{10} - \frac{1}{20}, i ., e . F = 20 c m$

Q. A thin convex lens of focal length 10 cm and a thin concave lens of focal length 20 cm are in contact. The combination acts as:

Concave lens of focal length 10.0 cm

Concave lens of focal length 20.0 cm

Convex or concave lens depending on refractive index of material of the lens

None of the above

F1​=f1​1​+f2​1​=101​−201​,i.,e.F=20cm

$\frac{1}{F} = \frac{1}{f _{1}} + \frac{1}{f _{2}} = \frac{1}{10} - \frac{1}{20}, i ., e . F = 20 c m$