A lens is made of flint glass (refractive index = 1·5).When the lens is immersed in a liquid of refractive index 1·25, the focal length
A. Increases to a factor of 1·25
B. Increases to a factor of 2·5
C. Increases to a factor of 1·2
D. Decreases to a factor of 1·2
Answer:B
A lens is made of flint glass (refractive index = 1·5).When the lens is immersed in a liquid of refractive index 1·25, the focal length
A. Increases to a factor of 1·25 B. Increases to a factor of 2·5 C. Increases to a factor of 1·2 D. Decreases to a factor of 1·2