Unit 2 Questions

Question 1

What two conditions need to be fulfilled in order for total internal reflection to occur?

Answer 1

• The ray has to be attempting to leave from a more dense medium.
• The angle between the ray and the normal to the interface must be greater than the critical angle.

Question 2

What is the meaning of hard?

Answer 2

A large force will only make a small scratch - it is difficult to scratch or dent.

Question 3

What is the meaning of brittle?

Answer 3

The material shows very little plastic deformation before breaking.

Question 4

What is the meaning of tough?

Answer 4

• The material can store a lot of energy before it breaks.
• The material can withstand lots of deformation.
• The material deforms plastically.

Question 5

What is the definition of diffraction?

Answer 5

The spreading out of a wave as it passes through a narrow slit or around an object.

Question 6

What is the definition of superposition?

Answer 6

The adding of two or more waves to give a resultant wave.

Question 7

Describe what happens during the polarisation of an electromagnetic wave

Answer 7

• An unpolarised wave oscillates in many directions.
• Once polarised, a wave oscillates in a single direction that is perpendicular to the direction of propogation.

Question 8

Why are results from an experiment accepted by the scientific community?

Answer 8

• There is experimental evidence.
• The experiment is supported by previous evidence.
• The experiment is reproducible.

Question 9

What does Huygens’ principle state?

Answer 9

Every point on a wavefront is a source of wavelets.