Waves

When a two-slit arrangement was set up to produce interference fringes on a screen using a monochromatic source of green light, the fringes were found to be too close together for convenient observation. It would be possible to increase the separation of the fringes by

• decreasing the distance between the slits and the screen

• increasing the distance between the source and the slits

• increasing the distance between the two slits

• increasing the width of each slit

• replacing the light source with a monochromatic source of red light

A parallel beam of monochromatic light of wavelength 600 nm is incident along the normal to a diffraction grating having 200 lines per millimetre. The maximum number of orders visible, to one side of the straight-through position, is

• 0

• 4

• 8

• 4000

• 8000

Plane-polarised light can be produced from unpolarised light by

• reflection from a sheet of glass

• total internal reflection at a water-air surface

• refraction through a glass prism

• passing it through a coloured filter

• passing it through a narrow slit

Which one of the following is not found with both sound waves and radio waves?

• Reflection

• Refraction

• Polarisation

• Diffraction

• Standing waves

A small loudspeaker connected to a source of alternating current is held just above the open end of a wide glass tube about 50 cm long, the lower end of which is closed. If the frequency of the alternating current is increased gradually from an initially low value to a value of about 1000 Hz, the intensity of the sound

• diminishes progressively

• increases progressively

• passes through a single maximum

• passes through a succession of maxima

• remains constant

The refractive index of transparent medium 1 is 1.60 and that of medium 2 is

1.30. A light ray travelling in air and first passing through medium 2 then through

medium 2 would travel in which of the following ways?:

• 
• 
• 
• 

The ray of light shown strikes the upper face of a glass block at an angle of 30° to

its surface. If the refractive index of the glass is 1.52 then the angle the light

makes with the lower surface inside the block will be close to:

• 61°

• 55°

• 48°

• 35°

Light is shone down into the glass block above so it just emerges into the air at the lower surface. The maximum angle x that the light can strike the inner surface of the block (measured to the normal) and still emerge into air is closest to:

• 40.3°

• 40.9°

• 41.1°

• 41.8°

If a diffraction grating, used to observe spectra, is replaced by one having twice as many rulings per millimetre the

1 angle of diffraction is double for every spectral line

2 gaps between the first and second order are narrowed

3 spectra all appear wider than before

• 1, 2 and 3 are all correct

• 1 and 2 only are correct

• 2 and 3 only are correct

• 1 only is correct

• 3 only is correct

In Young's double slit experiment, with a monochromatic light source, the separation of the interference fringes is increased by

1 increasing the wavelength of the light

2 decreasing the distance between the slits and the screen

3 increasing the separation of the slits

• 1, 2 and 3 are all correct

• 1 and 2 only are correct

• 2 and 3 only are correct

• 1 only is correct

• 3 only is correct