If light in air is incident at 20°, at what angle is it refracted in glass?

To determine the angle at which light is refracted in glass, we need to use Snell's law. Snell's law relates the incident angle (θ1), the refracted angle (θ2), and the refractive indices of the two mediums involved.

In this case, the incident medium is air and the refractive medium is glass. The refractive index of air is approximately 1.00, and the refractive index of glass depends on the type of glass but is typically around 1.50.

Snell's law can be written as:

n1 * sin(θ1) = n2 * sin(θ2)

where n1 is the refractive index of the incident medium, θ1 is the incident angle, n2 is the refractive index of the refractive medium, and θ2 is the refracted angle.

Let's calculate the refracted angle:

n1 * sin(θ1) = n2 * sin(θ2)

1.00 * sin(20°) = 1.50 * sin(θ2)

sin(θ2) = (1.00 * sin(20°)) / 1.50

sin(θ2) ≈ 0.342

To find the angle θ2, we can take the inverse sine (or arcsine) of this value:

θ2 ≈ arcsin(0.342)

Using a calculator, θ2 ≈ 20.5° (rounded to one decimal place).

Therefore, the light is refracted in glass at an angle of approximately 20.5°.