# Refraction of Light question assistance needed

• Issy
In summary, the student is preparing for a physics exam and is attempting an old exam paper. They are stuck on a question involving the angle of refraction in an oil layer with given refractive indices. The student's calculation gives an answer that does not match any of the multiple choice options. After getting help, they realize their mistake and are reminded to not be afraid of making mistakes and asking for help as it is a part of the learning process.
Issy
As revision for my upcoming physics exam, I'm doing an old exam paper from a previous year of the course, for which the answers aren't published. However, I'm stuck on a basic angle of refraction question:
"A light ray makes an angle of 35degrees to the surface of an oil layer. [A diagram is attached, which shows the light ray traveling through air until it hits the oil surface]. The air's n=1.00, and the oil''s n=1.47. What is the angle of refraction of the light ray in the oil?"

It's a multichoice answer, and the answers are A) 35degrees, B) 56.1degrees, C) 55.9degrees, D) 33.9degrees, and E) 67.7.
However when I use the n1*sin(theta1) = n2*sin(theta2) method, my answer is always equal to 22.97degrees? Which is equal to none of the multichoice answer values? And because there are no published answers, I can't check the correct answer.
Have I done something wrong? Or is there a mistake in the exam paper? Thank you for any and all help!
[P.S. my calculator is definitely set in degrees.]

Relevant equations:
n1*sin(theta1) = n2*sin(theta2)

The attempt at a solution:
1 * sin(35) = 1.47 * sin(theta2), therefore sin-1 (sin(35)/1.47) = theta2 = 22.97degrees.

Try 90o - 35o as the incident angle.
The incident angle for Snell's law is measured with respect to the normal to the surface.

andrevdh said:
Try 90o - 35o as the incident angle.
The incident angle for Snell's law is measured with respect to the normal to the surface.

Thank you very much! A dumb mistake on my part; you've saved me from embarrassing myself in front of my lecturer when I went to ask him for help, and the extra info at the bottom was also very helpful, thank you again!

Don't be afraid to make mistakes or ask questions (and hopefully do not break anything in the process). That is (mostly) how we learn.

## 1. What is refraction of light?

Refraction of light is the phenomenon in which light changes direction as it passes through a medium with different optical properties, such as air, water, or glass. This change in direction is due to a change in the speed of light.

## 2. What causes refraction of light?

Refraction of light is caused by the change in the speed of light as it passes through a medium with different optical properties. This change in speed is due to the change in density of the medium, which affects the way light waves travel through it.

## 3. How does refraction of light affect the appearance of objects?

Refraction of light can affect the appearance of objects by causing them to appear distorted or shifted when viewed through a medium with different optical properties. This is because the light rays are bent as they pass through the medium, causing the object to appear in a different location or with a different shape.

## 4. What is the difference between refraction and reflection?

Refraction and reflection are two different properties of light. Refraction is the bending of light as it passes through a medium with different optical properties, while reflection is the bouncing back of light when it hits a surface. Refraction changes the direction of light, while reflection does not.

## 5. How is refraction of light used in everyday life?

Refraction of light is used in a variety of everyday life applications, such as in eyeglasses, lenses, and cameras. It is also used in the production of mirrors, optical fibers, and prisms. Refraction is also the basis for many optical illusions, such as the bending of a straw in a glass of water.

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