Light

Question 1

Describe the types of reflection.

Answer 1

Reflection from a smooth surface in a single direction is called specular reflection. Reflection from a rough surface causes scattering: this is called diffuse reflection.

Question 2

How is the colour of an opaque object determined?

Answer 2

It depends on which wavelengths of light are more strongly reflected. If all wavelengths are reflected equally the object appears white. If all wavelengths are absorbed the objects appears black.

Question 3

Compare opaque, translucent, and transparent objects.

Answer 3

Opaque objects do not transmit any wavelengths, transparent objects transmit all wavelengths, translucent objects transmit at least some wavelengths.

Question 4

What type of electromagnetic wave is always being absorbed and emitted?

Answer 4

All bodies (objects), no matter what temperature, emit and absorb infrared radiation. The hotter the body, the more infrared radiation it radiates in a given time.

Question 5

What is a perfect black body?

Answer 5

A perfect black body is an object that absorbs all of the radiation incident on it. A black body does not reflect or transmit any radiation. Since a good absorber is also a good emitter, a perfect black body would be the best possible emitter.

Question 6

How is temperature change related to a body’s interaction with radiation?

Answer 6

The temperature of a body increases when the body absorbs radiation faster than it emits radiation, and vice versa.