5.2 - TIR and Lenses

Question 1

What is the refractive index of a material through which light travels at a speed of ‘v’ ?

Answer 1

n = c/v
c is the speed of light in a vacuum

Question 2

State the equation linking the refractive indexes and angles at an interference between two mediums

Answer 2

n1 Sin0 = n2 Sin0

Question 3

What is the critical angle

Answer 3

the angle of incidence for which the angle of refraction is 90 and all the light passes along the boundary between the mediums. Beyond this angle all light will be reflected

Question 4

What is the equation to calculate a critical angle

Answer 4

sin C = 1/n

Question 5

What is TIR

Answer 5

TIR 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.

Question 6

What is the focal length of a converging lens

Answer 6

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

Question 7

what is the focal length of a lens and how do u calculate the power

Answer 7

• distance between the centre of the lens and the focal point
• power = 1 / focal length

Question 8

What is a real image

Answer 8

one that can be projected onto a screen and is always inverted - are the consequence of light meeting at a focal point

Question 9

What is a virtual image

Answer 9

the consequence of light rays appearing to meet at a point and cannot be projected onto a screen

Question 10

What is the magnification equation

Answer 10

Magnification = image height / object height