User:Inconspicuum/Physics (A Level)/Optics Questions

Lenses

1. A lens has a focal length of 10 cm. What is its power, in dioptres?
2. Light reflected off a cactus 1.5 m from a 20 D lens forms an image. How many metres is it from the other side of the lens?
3. A lens in an RGB projector causes an image to focus on a large screen. What sort of lens is it? Is its power positive or negative?
4. What is the focal length of a 100 D lens?
5. The film in a camera is 5 mm from a lens when automatically focused on someone's face, 10 m from the camera. What is the power of the lens?
6. The light from a candle is enlarged by a factor of 0.5 by a lens, and produces an image of a candle, 0.05 m high, on a wall. What is the height of the candle?

Refraction

1. A ray of light is reflected from a mirror. Its angle to the normal when it reaches the mirror is 70°. What is its angle of reflection?
2. The speed of light in diamond is 1.24 x 10⁸ m/s. What is its refractive index?
3. The refractive index of ice is 1.31. What is the speed of light in ice?
4. A ray of light passes the boundary between air and a transparent material. The angle of refraction is 20°, and the angle of incidence is 10°. What is the speed of light in this material? Why is it impossible for this material to exist?
5. What is the critical angle of a beam of light leaving a transparent material with a refractive index of 2?