Investigating refraction (Practical)

Question 1

Describe the method of a practical to investigate refraction using a ray box and a glass block

Answer 1

1) place the block on A3 paper and draw around it
2) draw the normal line - at right angles to the side of the block the light will be on
3) using a protractor, mark the angles of incidence from 0 degrees to 80 in 10 degree intervals
4) starting with the 0 angle, direct the light ray towards the block and mark its exit point
5) remove the glass block and join the exit point to the point of incidence with a straight line
6) repeat for other angles

Question 2

State the two things that can change when a light ray is refracted [2]

Answer 2

speed and direction

Question 3

Draw a table of results for a light ray travelling from air into a block of water instead of a block of glass [2]

Answer 3

angles of refraction are less than their corresponding angles of incidence, angles of refraction are greater than the corresponding angles of refraction for those in the glass block

(water is less dense than glass)

Question 4

Explain how the (a) frequency and (b) wavelength of a light ray are affected when it enters glass from air [4]

Answer 4

a) frequency does not change because it is determined by the oscillating source that produces the wave and remains constant regardless of speed of wavelength
b) wavelength decreases because the wave speed decreases and the frequency decreases

Question 5

Conclusion of the practical

Answer 5

when a light ray travels from air into a glass block, its direction changes and the angle of refraction will be less than the angle of incidence unless it is travelling along the normal

Question 6

There are two angles of refraction, and two angles of incidence.

Which pairs are equal?

Answer 6

r = r

i = i