Question

Focal length of four convex lens 20,10,15,5, mote power is

Answer 1

Powers are →( 0.05 ) , ( 0.1 ) , ( 0.0667 ) , ( 0.2 )

Explanation

Mathematically power of a convex lens is reciprocal of the focal length.

Power ( P ) = 1 ÷ Focal length ( F )

So ,

if ,

Focal length = 20 units

• Power = 1 ÷ 20
• Power = 0.05 units^-1

Focal length = 10 units

• Power = 1 ÷ 10
• Power = 0.1 units^-1

Focal length = 15 units

• Power = 1 ÷ 15
• Power = 0.0667units^-1

Focal length = 5 units

• Power = 1 ÷ 5
• Power = 0.2 units ^-1