LIGHT AND WAVES REVISION YEAR 11
This information is required for questions 1 and 2
A, B, C and D represent the possible contents of a box. In each case, select the probable contents.
Question 1.
Question 2.
Question 3.
White light is passed through an inverted Perspex prism, as shown.
A
B
C
D
White light
Deduce which one is red light
A.
B.
C.
D.
Question 4.
In which of the following ray diagrams is light passing CORRECTLY through a glass block?
A.
B.
C.
D.
Question 5.
The best explanation of how optical fibres work in a fibre optic cable is
A. Light travels down the fibres and is reflected back once it hits the gut section and this is then recorded in the human
eye
B. As the light travels down the fibre it hit the edge of the glass at an angle larger than the critical angle and hence is
transported
all the way down the fibre and back after being reflected off the object.
C. The critical angle is what is required for light to stay inside a glass tubing for ever. Some energy is lost.
D. Critical angle is the angle of incidence where the refracted ray lies on the surface
Question 6. A beam of violet light ( = 409nm) enters water (n = 1.33) with an incidence angle of 250.
(a.)
(b.)
(c.)
(d.)
What is the speed of the beam in the water?
What is the frequency of the light wave inside the water?
What is the wavelength of the light wave inside the water?
What is the angle of refraction?
Question 7. A converging lens with a 40cm focal length forms an image of a 10cm high object placed 50cm from the
lens.
(a.) Use the lens equation and a rough ray diagram to find the position of the image?
(b.) How high will the image be?
Question 8. An object is placed 15cm in front of a convex mirror which has a focal length of 10cm.
(a.) Find the location of the image using the mirror equation and a suitable ray diagram.
(b.) Is this a real or virtual image?
Question 9. The radius of curvature of a mirror is approximately equal to :
A.
B.
C.
D.
the focal length of a mirror.
½ of the focal length of the mirror.
2 times the focal length of the mirror.
3 times the focal length of the mirror.
Question 10. x rays are
A.
B.
C.
D.
magnetic in nature.
electromagnetic in nature.
in the visible spectrum only.
electric in nature
Question 11. A student sends four pulses per second down a slinky which is 6 metres long.
She notices that there are 8 crests and 8 troughs. What is the speed of the waves?
A. 0.75 ms-1 B. 2ms-1 C. 1.5ms-1 D. 3ms-1 E. 0.375ms-1
Question 12. When a surface wave in water goes from deep to shallow water what happens ?
A.
B.
C.
D.
E.
The frequency of the waves increases.
The wavelength increases.
Nothing changes.
The wavelength decreases.
The frequency decreases.
Question 13. Red light has a wavelength of 7  10-7m. What is its frequency?
A. 210 Hz B. 4.89  108 Hz C. 4.29  1014 Hz D. 2.33  10-15 Hz E. 1.43  106 Hz.
Question 14. How long would an air column have to be to have a fundamental
frequency of 512 Hz if it was :
(a.) an open column?
(b.) a closed column?
( speed of sound = 343ms-1 )
Question 15 The diagram below represents different sound waves :
(a.)
(b.)
(c.)
(d.)
(e.)
Which diagram from the previous page represents :
(a.) the quietest sound?
(b.) the lowest pitch sound?
Question 16. Light of wavelength 400nm shines through slits 5  10-5 m apart. How far will
the first order bright lines be from the central bright band if the light shines
on a screen 2 m away?
Question 17 A string is 120 cm long. It has a resonant frequency (fn) of 42.5 Hz and another resonant frequency (fn+3) of
68 Hz.
Draw the standing wave and calculate the distance between nodes for the 68 Hz frequency
Question 18. (to solve a very challenging problem: assemble several pieces of information and integrate them to complete a task,
multistepped)
A 45°/45° heavy flint glass prism is placed in a beaker of water. A ray of light from a light box is incident on one side
of the prism. Describe the path of the light once it enters the water. (ng=1.56, nw=1.33).
Question 19. How far must an object be placed behind a convex lens of focal length 20 cm in order that the image is
magnified 3 times and remains upright?
Question 20. When yellow sodium light ( = 589nm) is used in a double slit experiment, the first order maximum is at
an angle of 0.0180. When the light is replaced by a second source of unknown wavelength, the second maximum occurs
at 0.0350. What is the unknown wavelength?
Question 21. The refractive index of transparent medium 1 is 1.30 and that of medium 2 is 1.60. A light ray traveling
in air and first passing through medium 2 then through medium 1 would travel in which of the following ways?:
A
B
C
D
Medium 2
Medium 1
Question 22. The ray of light shown strikes the upper face of a glass block at an angle of 40o to its surface. If the
refractive index of the glass is 1.52, what will be the angle the light makes with the lower surface inside the block?
This diagram is used
for questions 22 and
23
AIR n = 1.00
40o
x
GLASS n = 1.52
Question 23. Light is shone down into the glass block (above diagram) so it just emerges into the air at the lower
surface. What will be the maximum angle that the light can strike the inner surface of the block (measured to the normal)
and still emerge into air?
Question 24. Light is shone onto face P of a 60o Perspex prism of refractive index 1.50 at an angle of 450 to the
normal, as shown.
60o
n = 1.50
P
45o
60o
Q
60o
What will be the angle that the ray will emerge, measured to the normal, from face Q?
Question 25. In a modern version of Fizeau’s method the speed of light can be determined by shining a laser through a
5-toothed wheel onto a distant mirror.
Distant
mirror
Laser
Rotating
wheel
Light
detector
The laser light goes out through a gap in the teeth, hits the mirror, then returns through the next gap to be detected by the
light detector. This can only occur if the time to go out and return corresponds to the time taken for one tooth to rotate to
the position of the next. The rate of rotation of the wheel can be gradually increased until the reflected light is detected.
In an experiment, light is just recorded returning by the detector when the rotation of the toothed wheel is exactly 2000
revolutions per second. If the distance from the laser to the mirror is 14 km, what will be the approximate value for the
velocity of light?
Question 26. A triangular prism of angle 300 is placed over a plane mirror. A ray of light from a ray box is shone
down at an angle of 450 to the surface of the prism so that it refracts by the prism and is then reflected from the mirror
beneath.
n = 1.53
450
300
Mirror
What will be the angle made to the glass surface as the ray emerges?
Question 27. In an experiment using the apparatus shown below the following 3 readings were taken for the angle of
incidence (i) and the angle of refraction (r)
Semicircular
glass block
r
i
Ray box
i
20o
40o
60o
r
12o
23o
32o
By averaging and using Snell’s Law, determine the refractive index of the glass
Question 28. Given the below diagram and that CA is 4.2cm and that BD is 3.1cm and that the medium that CA is air
(n=1.01) calculate the index of refraction of the block.
Question 29 Draw the resulting pulses after each of the following collisions.
(a.)
free
end
(b.)
heavy spring
light spring
Question 30. Draw the resulting wave form which would result after 3 seconds.
Both pulses are travelling at 1.5cms-1.
0cm
2cm
4cm
6cm
8cm
10cm
12cm
14cm
16cm
1cm
2cm
Question 31 Lyall is playing some Abba on his geetar. Louisa takes a photo of him while he is playing. The resulting
photo reveals a standing wave on his G string. The string is 1.2m long. Louisa observes 4 nodes (not counting the fixed
ends).
What is the wavelength of the standing wave?
Draw a diagram of the wave pattern.
Question 32. Two plane mirrors AB and BC are placed at 700 to each other as shown :
A ray of light PQ strikes mirror AB at an angle of 300 to the mirror.
Copy the diagram and continue the ray PQ to show its path after reflection by the second mirror. Show the size of any
angles necessary to specify the ray’s exact path.
Question 33. Describe the conditions which enable an image to be the same size as the object when using a mirror or a
lens.