WAVES

 

1. The equation of a travelling wave is y = 0.2sinπ(6t – 40x)

(y and x in metres and t in seconds), for this wave find:

(a) the amplitude.

(b) the frequency.

(c) The wavelength.

(d) the speed.

(e) The phase relationship between two points on the wave 10cm apart.

 

2. In a wedge interference experiment two glass slides of length 8.0cm are placed in contact at one end and the other ends are separated by a thin piece of paper. When the wedge is illuminated with light of wavelength 500nm, fringes with a separation of 0.80mm are observed. Calculate the thickness of the piece of paper.

 

3. A lens is coated with a transparent substance of refractive index 1.40. Calculate the minimum thickness required to produce destructive interference of green light of wavelength 540nm.

 

4. Two parallel slits with a separation of 200μm are illuminated by monochromatic light of wavelength 480nm. Fringes with a separation of 3.6mm are produced on a nearby screen. Calculate the distance from the slits to the screen.

 

5. A beam of light travelling in air is plane polarised on reflection from water of refractive index 1.33. Find:

(a) The polarising angle.

(b) The angle of refraction for the light in water.