Practice Question

1.When an electromagnetic wave strikes a substance what can happen to the wave?

When electromagnetic waves strike a substance, they can be reflected, refracted, absorbed or transmitted.

2.Define refraction.

Refraction is the change in direction of a wave as it passes the boundary from one medium to another, resulting from a change in velocity of the wave.

3. Suggest why glass can cause significant refraction of visible light rays, but radio waves only show a small amount of refraction.

Glass refracts light rays more than radio waves because light rays have a shorter wavelength compared to radio waves

4. Describe an experiment to investigate the emission of infrared radiation from different surfaces

Leslie’s cube (a metal cube with different surfaces: matt black, matt white, shiny black, and shiny metallic)

Infrared thermometer

Boiling water

Heatproof mat

1.Prepare the Leslie’s cube – Fill it with boiling water and place it on a heatproof mat.

2.Wait a few minutes – Allow the surfaces to reach a steady temperature.

3.Measure infrared radiation – Hold an infrared thermometer at the same distance from each surface and record the temperature or IR radiation emitted.

Repeat measurements – Take multiple readings for accuracy and consistency.

The matt black surface emits the most infrared radiation.

The shiny metallic surface emits the least infrared radiation.

The matt white and shiny black surfaces emit intermediate amounts.