Alight ray in air is incident on an air to glass boundary at an angle of 40 degrees and is refracted in the glass of 25 degrees with the normal. what is the index of refraction of the glass? a. 1.10 b. 1.25 c. 1.33 d. 1.52 !

D

Explanation:

Snell's law states:

n₁ sin θ₁ = n₂ sin θ₂

where n is the index of refraction and θ is the angle of incidence (relative to the normal).

The index of refraction of air is approximately 1.  So:

1 sin 40° = n sin 25°

n ≈ 1.52

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27