0
You visited us 0 times! Enjoying our articles? Unlock Full Access!
Question

# Diameter of plano-convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2×108m/s, the focal length of the lens is:15 cm10 cm20 cm30 cm

A
15 cm
B
30 cm
C
20 cm
D
10 cm
Solution
Verified by Toppr

#### The lens is as shown in the figure.To determine the radius of curvature R of the curved surface, we can writeR2=32+(R−310)2Solving this, we getR=15.15cmSpeed of light in any medium is cμ where c=3×108m/s and μ is the refractive index.For the lens, cμ=2×108m/sμ=3×1082×108=1.5Putting these values in the lens makers formula for plano convex lens, we have,1f=(μ−1)(1R)=(1.5−1)(115.15)cm−1Solving this, we get f≈30cm

15
Similar Questions
Q1
Diameter of plano-convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2×108m/s, the focal length of the lens is:
View Solution
Q2
Diameter of plano – convex lens is 6cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2×108 m/s, the focal length of the lens is:
View Solution
Q3
The diameter of aperture of a plano-convex lens is 6 cm and its maximum thickness is 3 mm. If the velocity of light in the material of the lens is 2×108m/s, its focal length is : (approximately)
View Solution
Q4
Diameter of a plano–convex lens is 6 cm and thickness at the centre is 3 mm. If the speed of light in the material of the lens is 2 108 m/sec, the focal length of the lens is
View Solution
Q5
The diameter of aperture of a plano-convex lens is 6 cm and maximum thickness is 3 mm. If velocity of light in material is 2×108 m/s, calculate focal length of the lens :
View Solution