Question

Suppose that a beachgoer uses two lenses from a pair of disassembled polarized sunglasses and places one on top of the other. What would he observe if he rotates one lens 90° with respect to the normal position of the other lens and looks through them directly at the sun overhead?

a. light with intensity reduced to about 25% of what it would be with one lens

b. Complete darkness since no light will be transmitted

c. Light with an intensity that is the same of what it would be with one lens

d. Light with an intensity reduced to about 50% of what it would be with one lens

Answer 1

a beachgoer uses two lenses from a pair of disassembled polarized sunglasses and places one on top of the other.

he rotates one lens 90° with respect to the normal position of the other lens and looks through them directly at the sun overhead

by rotating one polarized sunglass 900 with respect to normal position of the other lens, the two lenses are crossed.

Using Malu’s law,

Intensity of light emerging through second polarizer is

I = Io/2 Cos2θ

Θ = 90 implies cos 90 = 0 and I = 0. Hence, no light is transmitted.

b. Complete darkness since no light will be transmitted