AS exams Definitions

Question 1

Resultant force

Answer 1

A single force which has the same effects as the sum of all the forces acting on a body

Question 2

Newton

Answer 2

Force causing 1 kg to have an acceleration of 1m/s^2

Question 3

Equilibrium

Answer 3

When all forces acting on a body in the same plane are balanced = zero net resultant force

Question 4

Phase difference

Answer 4

The difference in the phases of two waves of the same frequency in radians

Question 5

Path difference

Answer 5

The difference in the distance travelled by two waves in terms of their wavelength

Question 6

Refraction

Answer 6

Change in the speed of a wave in a new medium

Question 7

Coherence

Answer 7

When phase difference is constant (constant phase relationship)

Question 8

Principle of superposition

Answer 8

When two or more waves of the same type meet, the resultant wave can be found by adding the displacements of the individual waves

Question 9

Power

Answer 9

Energy per unit time

Question 10

Kirchoffs second law

Answer 10

In any closed loop, the sum of the emf’s is equal to the sum of the products of the current and resistance.

Question 11

Node

Answer 11

A stationary point on a wave where destructive interference occurs = zero displacement

Question 12

Antinodes

Answer 12

A point of maximum displacement where constructive interference occurs

Question 13

Progressive wave

Answer 13

Transfers energy in direction of the wave
Along 1 wavelength all points are out of phase
All particles have the same amplitude

Question 14

Stationary wave

Answer 14

No transfer of energy
Alternate out and in phase
Amplitude varies according to the position (zero at the nodes)

Question 15

Fundamental mode of vibration

Answer 15

The lowest frequency and the longest wavelength that can be produced. Where the length of the string is half the wavelength of the note.

Question 16

Potential

Answer 16

Energy shared between resistors

Question 17

Terminal velocity

Answer 17

Highest velocity reached by an object when it is no longer accelerating

Question 18

Lost volts

Answer 18

Difference between the emf and the P.d

Question 19

Photon

Answer 19

A type of quantum meaning that one photon has a discrete amount of energy.

Question 20

Electronvolt

Answer 20

The kinetic energy gained by an electron when accelerated through a potential difference of 1 volt

Question 21

Interference

Answer 21

Superposition of coherent waves

Question 22

Moment of a force

Answer 22

The turning effect of a single force. Force x perpendicular distance between force and pivot point.

Question 23

Torque

Answer 23

Turning effect due to a couple, one of the forces multiplied by perpendicular distance

Question 24

Couple

Answer 24

When two forces have the same magnitude but are in opposite directions and don’t act through the same line of action.

Question 25

Kirchoffs first law

Answer 25

Sum of all the currents entering a junction is always equal to the sum of all the currents leaving the junction

Question 26

Mean drift velocity

Answer 26

Average velocity of an electron in a circuit