Name:__________________________________  		Wave Phenomena Summer Work
1.	Light travels from air into glass as shown below.
		
	What is the refractive index of glass?
A.			B.			C.			D.	

2.	Which of the following correctly describes the change, if any, in the speed, wavelength and frequency of a light wave as it passes from air into glass?
Speed	Wavelength	Frequency	
A.	decreases	decreases	unchanged	
B.	decreases	unchanged	decreases	
C.	unchanged	increases	decreases	
D.	increases	increases	unchanged	

3. 	Plane wavefronts are incident on a boundary between two media labelled 1 and 2 in the diagram. The diagram of the wavefronts is drawn to scale.

	The ratio of the refractive index of medium 2 to that of medium 1 is
A.	0.50		B.	0.67.		C.	1.5.		D.	2.0.

4.	An orchestra playing on boat X can be heard by tourists on boat Y, which is situated out of sight of boat X around a headland.
		
The sound from X can be heard on Y due to
A.	refraction.				B.	reflection.
C.	diffraction.				D.	transmission.

5.	Two coherent point sources S1 and S2 emit spherical waves.

	Which of the following best describes the intensity of the waves at P and Q?

	P	Q	
A.	maximum	minimum	
B.	minimum	maximum	
C.	maximum	maximum	
D.	minimum	minimum	

6.	Light of wavelength λ is emitted by two point sources. The light passes through a circular aperture of diameter b and is received by an observer. The angular separation of the sources from the observer’s position is θ. The sources are not resolved by the observer. Which of the following mathematical relationships applies?
		
A.	θ < 1.22				B.	θ > 1.22
C.	θ = 1.22				D.	θ = 

7.	A beam of coherent light is incident on a single slit of width b. After passing through the slit, the light is incident on a screen at a distance D from the slit.
		
	Which of the following changes, carried out separately, in respect of b and D will result in an increase in width of the first diffraction maximum formed on the screen?

	b	D	
A.	decrease	increase	
B.	increase	increase	
C.	decrease	decrease	
D.	increase	decrease	

8.	In two separate experiments monochromatic light is incident on a single slit. The diagrams show the diffraction patterns obtained on a screen far from the slit. In the top diagram the wavelength of light is λ1 and the slit width is b1. In the bottom diagram the wavelength of light is λ2 and the slit width is b2.

	In each experiment the distance between the slit and the screen is the same. Which of the following may be deduced?
A.					B.	
C.	b1 < b2				D.	λ1 > λ2

9.	A parallel beam of monochromatic light of wavelength λ passes through a slit of width b. After passing through the slit the light is incident on a distant screen. The angular width of the central maximum is
A.	2 radians.			B.	 radians.
C.	2 degrees.			D.	 degrees.

 10.	The images of two sources are just resolved. Which of the following is a correct statement of the Rayleigh criterion for this situation?
A.	The central maximum of the diffraction pattern of one source must coincide with the central maximum of the diffraction pattern of the other source.
B.	Light from the sources must pass through a circular aperture.
C.	Light from the sources must be coherent.
D.	The first minimum of the diffraction pattern of one source must coincide with the central maximum of the diffraction pattern of the other source.

11.	Two galaxies with an angular separation at the observer of 5.0 × 10–4 radians are observed with a radio telescope. Both galaxies emit radio waves of wavelength 2.5 × 10–2 m.
	The images of the galaxies are just resolved by the telescope. The diameter of the circular collecting dish of the telescope is
A.	61 m.
B.	50 m.
C.	30 m.
D.	25 m.
 
12.	An optically active substance
A.	completely absorbs polarized light.
B.	unpolarizes polarized light.
C.	polarizes unpolarized light.
D.	rotates the plane of polarization.

13.	Unpolarized light of intensity I0 is incident on a polarizer. The transmitted light is then incident on a second polarizer. The axis of the second polarizer makes an angle of 60° to the axis of the first polarizer.

The cosine of 60° is The intensity of the light transmitted through the second polarizer is
A.	I0.		B.			C.			D.	

14.	The diagram shows sunlight reflected from a lake surface. The reflected sunlight is plane-polarized.
		
	The plane of polarization of the reflected sunlight is
A.	parallel to the lake surface.
B.	perpendicular to the lake surface.
C.	parallel to the direction of the reflected sunlight.
D.	in the plane of the diagram.

15.	The diagram represents a beam of unpolarized light incident on a diamond.
		
	The refractive index of the diamond is n.
	At an angle θp, the beam reflected from the diamond is plane polarized normal to the page. The angle θp is
A.	tan–1 n.
B.	tan–1.
C.	sin–1.
D.	cos–1.

16.	This question is about interference.
(a)	Light from a laser is incident on two very narrow slits A and B.

(diagram not to scale)
	Point C on the screen is directly opposite the midpoint of the slits.
 (i)	On the axes below, sketch the variation with angle θ of the intensity of the light on the screen.

(2)

(ii)	The separation of the slits is 0.120 mm and the wavelength of the light is
6.80 × 10–7 m. The distance between the slits and the screen is 1.40 m. Calculate the separation of the bright fringes on the screen.
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(2)

(b)	Slit A is covered with a transparent piece of glass. The effect of the glass is to increase the path length of the light from the slit to the screen by half a wavelength. It may be assumed that the amount of light absorbed by the glass is negligible. State and explain the effect(s), if any, of the glass on the
(i)	intensity pattern you have drawn in (a)(i).
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(2)
 
(ii)	separation of the bright fringes calculated in (a)(ii).
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(2)

17.	This question is about interference and diffraction.
	Light from a laser is incident on two slits of equal width. After passing through the slits, the light is incident on a screen. The diagram below shows the intensity distribution of the light on the screen.

(a)	The wavelength of the light from the laser is 633 nm and the angular separation of the bright fringes on the screen is 4.00 ´ 10–4 rad. Calculate the separation of the slits.
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(3)
 
(b)	Light from the laser is incident on many slits of the same width as the widths of the slits above. Draw, on the above diagram, a possible new intensity distribution of the light on the screen.
(2)
(c)	The laser is replaced by a source of white light. Describe, if any, the changes to the fringes on the screen.
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(2)
 
18.	This question is about thin film interference.
	A transparent thin film is sometimes used to coat spectacle lenses as shown in the diagram below.

(a)	State the phase change which occurs to light that
(i)	is transmitted at boundary A into the film.
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(1)
(ii)	is reflected at boundary B.
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(1)
 (iii)	is transmitted at boundary A from the film into the air.
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(1)
19.	This question is about the Rayleigh criterion.
(a)	Light from two monochromatic distant point sources, S1 and S2, is incident on a narrow slit. After passing through the slit, the light is incident on a screen.

	On the axes below, draw the intensity distribution of the diffracted light on the screen from each source when the images of S1 and S2 are just resolved according to the Rayleigh criterion.

(3)
 (b)	A woman views an approaching car at night. The apertures of her eyes are each of diameter 3.0 mm. The headlamps of the car are separated by a distance of 1.2 m and emit light of wavelength 400 nm.
	Calculate the distance of the car from the woman at which the images of the two headlamps are just resolved.
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(3)
20.	This question is about the diffraction of light.
(a)	(i)	Describe what is meant by the diffraction of light.
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(2)
(ii)	A parallel beam of monochromatic light from a laser is incident on a narrow slit.
The diffracted light emerging from the slit is incident on a screen.
		
(not to scale)
	The centre of the diffraction pattern produced on the screen is at C. On the axes sketch a graph to show how the intensity I of the light on the screen varies with the distance d from C.
		
(3)
(iii)	The slit width is 0.40 mm and it is 1.9 m from the screen. The wavelength of the light is 620 nm. Determine the width of the central maximum on the screen.
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(3)

(b)	(i)	When two separate lasers are used as sources, the images of the slit formed by the light from each laser are resolved. State what is meant by the term resolved in this context.
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(1)
 
(ii)	A car, with its two headlights switched on, is approaching an observer who has good eyesight. Outline why, at a long distance from the observer, the images of the headlights of the car are not resolved by the observer.

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(4)