Mirrors angles and rays?

Question

1. A ray of light is incident on a plane mirror and the angle of incidence is 50°.

a) how big is the angle of reflection?

b) what is the angle between the incident ray and the mirror surface?

2. AO is a ray of light incident on a surface and OB is the reflected ray.

a) on the ray diagram, draw the surface and the normal:

http://www.flickr.com/photos/99973477%40N03/9737941325/

b) what is the size of the angle of incidence?

3. The following waves are travelling towards each other:

http://www.flickr.com/photos/99973477%40N03/9740150528/

a) sketch the patterns at the instant their peaks overlap

b) Sketch the pattern after they passed through each other

c) what is the term used for this kind of interference?

4. The speed of an object equals the distance it travels divided by the time it takes. 

a) Calculate the time for the light from the sun to reach earth if they are 1.49 x 10^11m apart.

b) Calculate the time to get to Neptune, when it's 4.50 x 10^12m from the Sun.

Answer 1

1)

Angle of incidence Өi=50°.

a)

Calculate the angle of reflection (Өr)

Өr=Өi=50°.

b)

Calculate the angle between the incident ray and the mirror surface(α)

α=90-Өi

   =90-50

   =40°.

 

 

Answer 2

Angle of incidence is zero

Answer 3

4)

Calculate the time for the light from the sun,

   Δt=2L/c

Here L is the distance and c is the speed of the light.

a)

Substitute 1.49 x 10^11m for L and 3 x 10^8 m/s in above formula

   Δt=2*1.49 x 10^11/3 x 10^8

     =993.33 s

       =16.55 min

b)

Substitute 4.50 x 10^12 m for L and 3 x 10^8 m/s in above formula

   Δt=2*4.50 x 10^12/3 x 10^8

     =30000 s

       =500 min