C - Waves - Light, Reflection and Refraction Flashcards
What type of waves are light waves?
transverse
Light waves can be ________ and __________.
Light waves can be reflected and refracted.
Describe an experiment to investigate the refraction of light.
Get two identical cups and place them side by side. Place a coin at the bottom of both cups. Fill one cup with water. Now look at the coins. Do they appear to be in the same place or even the same depth?You can also make a hidden coin appear as if by magic. This time just use one cup. Put the coin in against one side of the cup. Move your head until you just can’t see the coin any more. Now pour in water and, alla kazam, it appears!
Describe an experiment to determine the refractive index glass.
We can find the value of n for a glass block by using a ray box and a semicircular block.To do the experiment it is necessary to try a few angles of incidence and measure both the angle of incidence and the refracted angle. You would complete a table as you go.
Describe the role of total internal reflection in the transmission of information along optical fibres.
Light entering a periscope meets a triangular prism. It is then reflected down the tube of the periscope where it meets another prism. Finally, it is reflected at this prism out to the observer.
State the meaning of the critical angle c
answer
A material has a reflective index of 1.5. Calculate the size of x.
sin i / sin r = n sin 48 / sin r = 1.5 sin 48 / 1.5 = sin r 0.743/1.5 = sin r 0.495 = sin r r = sin-1 0.495 r = 29.7o x = 90 - 29.7 = 60.3o
A material has a refractive index of 1.45. Calculate the size of x.
sin i / sin r = n sin i / sin 30 = 1.45 sin i / 0.5 = 1.45 sin i = 1.45 x 0.5 sin i = 0.725 i = sin-1 0.725 = 46.5o x = 90 - 46.5 = 43.5o
A material has a refractive index of 1.35. Calculate the size of x.
53.7
A material has a refractive index of 1.3. Calculate the size of x.
sin i / sin r = n sin i / sin 40 = 1.3 sin i / 0.643 = 1.3 sin i = 1.3 x 0.643 sin i = 0.836 i = sin-1 0.725 = 56.7o x = 90 - 56.7 = 33.3o
Describe the role of total internal reflection in the transmission of information along optical fibres.
In recent years, the biggest use of total internal reflection is in transmitting information using fibre optics. Light travelling along an optical fibre is continuously reflected along the length of the fibre. No light can escape from the fibre. The light can be modulated to carry information.
