5.2 - TIR and Lenses

State the equation used to calculate intensity

I = P/A

P is the power

A is the area

What is the refractive index of a material through which light travels a speed of 'v'?

n = c/v

where c is the speed of light in a vacuum

State the equation linking the refractive index and angles at an interface between two mediums.

n₁sinθ₁ = n₂sinθ₂

What is the critical angle?

The angle of incidence for which the angle of reflection is 90⁰ and all the light passes along the boundary between the mediums. Beyond this angle all light will be reflected.

State the equation used to calculate a critical angle

sinC = 1/n

What is total internal reflection?

Total internal reflection is where all the light is reflected back at the boundary between two mediums. It occurs when light is incident at an angle greater than the critical angle.

What is the focal point of a converging lens?

The single point where the parallel rays of light entering the lens converge to.

What is the focal length of a lens?

The distance between the centre of the lens and the focal point

What is the equation used to calculate the power of a lens?

Power = 1/ Focal Length

How do you calculate the total power of a combination of thin lens?

P = P₁+P₂+P₃+...

What is a real image?

A real image is one that can be projected onto a screen and is always inverted. Real images are the consequence of light meeting at a focal point.

What is a virtual image?

Virtual images are the consequence of rays of light appearing to meet at a point.

They cannot be projected onto a screen.

State the equation used to calculate the magnification of an image

Magnification = Image Height / Object Height

What is plane polarisation?

Plane polarisation is when the oscillations of a wave are restricted to a single plane.