Diffraction, Refraction, Interference, Intensity, Polarisation, Standing Waves

1. The effects of diffraction are clearest in a demonstration when two quantities are similar. What are these quantities?

• A. Frequency and gap size
• B. Wavelength and gap size
• C. Wavelength and amplitude
• D. Gap size and amplitude

2. Which of the following diagrams best shows light wavefronts passing from left to right through a block of glass? (Note - not all wavefronts are shown).    3. A light ray passes from water into glass. The velocity of light in water is 2.30 x 108 ms-1 and in the glass is 2.00 x 108 ms-1. The refrective index of the water / glass boundary is

• A. 1.15
• B. 2.00
• C. 2.30
• D. 4.60

4. A light ray is incident on a glass block as shown. The refractive index of the glass/air boundary is 1.5 and the value of sin(300) is 0.5 . The value of sin (i) will be

• A. 3
• B. 1.33
• C. 0.5
• D. 0.75 5. Total internal relection can occur when light is trapped inside glass . This is used in optical fibres. To ensure total internal reflection occurs and the light ray remains inside the glass,

• A. the refractive index of the glass must be small and the angle θ must be small
• B. the refractive index of the glass must be small and the angle θ must be large
• C. the refractive index of the glass must be large and the angle θ must be small
• D. the refractive index of the glass must be large and the angle θ must be large

6. The intensity I of sound waves is measured at a distance x away from a loud speaker. The amplitude of the sound waves measured is A.

If the amplitude is increased to 4A and then the distance increased to 2x, the measured intensity will be

• A. I / 2
• B. 2 I
• C. 4 I
• D. 8 I

A laser is directed at two narrow silts as shown in the diagram below. Diffraction occurs, and the two rays P and Q arrive at a point on the screen. 7. Destructive interference between the 2 rays will occur if

• A. the path difference is λ
• B. the path difference is λ/2
• C. the slit seperation is λ
• D. the slit seperation is λ/2

8. The adding together of two waves like this is correctly termed the

• A. sumation of waves
• B. superposition of waves
• C. negation of waves
• D. vector addition of waves

9. Two waves will produce constructive interference if the phase difference is

• A. 7200
• B. 5400
• C. 4500
• D. 1800

10. An interference pattern will only occur between any two waves if

• A. the amplitude is the same
• B. the phase difference is the same
• C. the angle of diffraction is the same
• D. the waves are from the same source