Light and geometric optics

Question 1

What are the 3 equations for convex and concave mirrors?

Answer 1

1/image distance + 1/object distance = 1/focal length
or 1/i + 1/o = 1/focal length

f = r/2

Magnification (m) = -(image length)/(object length)

Question 2

What are the rules of reflection?

Answer 2

the angle of incidence (I) = the angle of reflection (R) when at the normal (N)

I, R and N all lie in the same plane

Question 3

What are the rules of refraction?

Answer 3

the incident ray, the refracted ray and the normal ray all lie in the same plane

the path of the ray is reversible

Question 4

What are the equation for working out the index of refraction?

Answer 4

n = c (speed of light in vacuum) / v (speed of light in medium)

n = c / v

Question 5

What is snell’s law?

Answer 5

sin(incidence angle)/sin(refracted angle) = n1/n2 = λ1/λ2

n is the refractive index (air is 1, water is 1.33, glass is 1.5)

Question 6

In what medium is the refraction angle (θ) smaller in?

Answer 6

the less optically dense medium

Question 7

When is the refraction angle (θ) closer to the normal?

Answer 7

when the wavelength is smaller

Question 8

When is a virtual image produced?

Answer 8

when a light ray strikes a mirror or a lens

Question 9

What is a real image?

Answer 9

when light rays passing through and can be projected on a screen.