Geometric Optics

Question 1

Refractive Index is usually given what symbol?

Answer 1

n

Question 2

What colour of light moves the slowest through a medium?

Answer 2

Blue

Question 3

What colour light travels fastest through a medium?

Answer 3

Red

Question 4

How a lens performs with respect to the splitting of light into its component colours is called what?

Answer 4

V-value or abbe number of a lens

Question 5

main problem of a lens with a Low V-value

Answer 5

higher dispersion of light, leading to lower performance and higher TCA

Question 6

Lenses above what V-value are considered to be a good lens?

Answer 6

45

Question 7

What is the ideal V-value of a lens?

Answer 7

As close to 60 as possible

Question 8

True or false?
The higher the refractive index of a lens, the lower the V-value is?

Answer 8

TRUE

Question 9

What is the meaning of relative curvature?

Answer 9

The means of comparing the curvature of two surfaces

Question 10

What is focal length?

Answer 10

The distance from the lens to its principal focus

Question 11

Where is light focused on a PLUS lens?

Answer 11

On the right hand side or behind the lens

Question 12

Where is the light focused on a MINUS lens?

Answer 12

On the left hand side or in front of the lens

Question 13

What information is needed to calculate the surface power of a lens?

Answer 13

Radius of curvature of the surface and the refractive index of the lens

Question 14

TRUE OR FALSE?
Increasing the refractive index of a lens will also increase the radius of curvature.

Answer 14

TRUE
This leads to a flatter lens

Question 15

Light spreading out from a point is said to be what?

Answer 15

Diverging

Question 16

Light coming into focus onto a point is said to be what?

Answer 16

Converging

Question 17

What is vergence?

Answer 17

The measure of how much a ray of light has converged or diverged.

Question 18

What is the unit for vergence?

Answer 18

Dioptre

Question 19

What symbol is given to define vergence?

Answer 19

L

Question 20

What happens when light is incident upon a plane surface?

Answer 20

The ray is reversed and travels back along its own path

Question 21

What is the first law of reflection?

Answer 21

The incident ray and the normal all lie in the same plane

Question 22

What is the second law of reflection?

Answer 22

The angle of incidence is equal to the angle of reflection

Question 23

What is the third law of reflection?

Answer 23

The image is as far behind the mirror as the object is in front of the mirror

Question 24

What happens when a ray of light moves from a low refractive index to a higher refractive index?

Answer 24

The ray of light will bend, or refract, towards the normal

Question 25

What are flat wavefronts called?

Answer 25

Plane waves

Question 26

What happens to light rays when entering a medium with a higher refractive index?

Answer 26

Wavelengths are compressed.

Question 27

What is lateral deviation?

Answer 27

Where a light ray is displaced sideways

Question 28

What is is a critical angle?

Answer 28

The refracted
ray is perpendicular to the normal and the normal is perpendicular to the surface, then the ray of
light must just skim the surface of the medium, without leaving it, but at the same time not being in
the prism

Question 29

What is the rule for an angle to be a critical angle?

Answer 29

The critical angle is an angle such that a ray of light going from a high density to a lower density medium cannot escape the higher index material

Question 30

TRUE OR FALSE?
The critical angle is the demarcation between refraction and reflection, where both takes place.

Answer 30

FALSE
The critical angle is the demarcation between refraction and reflection, where neither takes place.

Question 31

The critical angle of a material is the inverse sine of what?

Answer 31

The critical angle of a material is the inverse sine of the reciprocal of the refractive index of that
material.