Module 4 - Key Definitions

Question 1

Electronvolt:

Answer 1

The energy transferred by an electron travelling through a potential difference of 1V.

Question 2

Ohm:

Answer 2

The resistance when 1 volt of potential difference produces 1 ampere of current.

Question 3

Kirchoff’s Second Law:

Answer 3

Sum of e.m.f.s around a loop = sum of p.d.s around the same loop; energy is conserved

Question 4

Progressive Wave:

Answer 4

A transfer of energy as a result of oscillations.

Question 5

Plane Polarised Wave:

Answer 5

A wave that only oscillates in one plane.

Question 6

Superposition (of two waves):

Answer 6

When two or more waves meet at a point, the resultant displacement is a sum of the displacements of each wave.

Question 7

Interference:

Answer 7

When two waves superpose at a point and there is a change in the overall displacement.

Question 8

What is the requirement for two waves to be coherent?

Answer 8

Constant phase difference between two waves.

Question 9

What is a photon?

Answer 9

A packet of energy

Question 10

Photoelectric effect:

Answer 10

Emission of photo-electrons from a surface when photons are incident on the surface.

Question 11

Line spectrum

Answer 11

Light emitted from atoms to produce a series of lines against a dark background.