# Understanding Light: Reflection, Refraction, and Lenses

Posted by justbypaul and classified in Physics

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## Lens

### What is a real image?

An image where real rays intersect

### What is a virtual image?

An image that appears to be coming from behind the mirror

### Describe the law of reflection as a relationship between the angle of incidence, the angle of reflection, and the normal.

The angle of incidence, angle of reflection and normal all lie in the same plane

### Describe the kinds of images that can be formed by plane mirrors.

Only virtual images, little distortion

Convex

Concave

Convex

Both curved

### What kind of images do convex mirrors form?

Opposite, upright, smaller, virtual

### What are three uses for convex mirrors?

Side mirrors in cars, store security, parking lots or parkades

### A lighted object is placed at the focal point of a concave mirror. Describe the light rays reflecting off the mirror.

Light rays hit the mirror and reflect parallel

### Describe how the positions of a mirror, incident ray, reflected ray, and normal are related.

Angle of incidence = angle of reflection, normal is always perpendicular

### How does your image in a mirror compare with looking directly at yourself?

Lateral inversion (right is left, left is right)

### Describe how light changes its direction when moving from one medium to another.

More dense to less dense: light bends away from normal
Less dense to more dense: light bends towards normal

Density

### Through which medium does light pass more quickly, one with a refractive index of 1.1 or one with a refractive index of 2.2?

Quicker through refractive index n =1.1

### What type of lens produces a real image?

Converging in most cases

### What type of lens produces a virtual image?

Diverging always, converging when do

Telescopes

### How is the focal point of a mirror different from the vertex?

F is where parallel light rays will converge
V is the centre point of a mirror

### What is the definition of refraction?

Bending of light as it passes at an angle through a different media

### Which substance refracts light more, water or glass? Explain why.

Glass, has a higher refractive index (n)

### What is the speed of light?

How fast light travels through a medium (299792.458 km/s)

### What is the definition of index of refraction?

The ratio of speed of light in a vacuum to the speed of light in a given medium

## Resources of light

### Incandescence:

Light emitted due to an object heating up (old fashioned light bulbs)

### Bioluminescence:

Living creatures that produce light (fireflies)

### Chemiluminescence:

Chemical reaction that produces light (glow stick)

### Phosphorescence:

Prolonged emission of light following exposure to UV light (glow in the dark t-shirts)

### Fluorescence:

Light produced during the exposure to UV light (compact fluorescent lightbulbs)