Exploring Yr 1 Definitions

Question 1

Electric current?

Answer 1

The rate of flow of charge.

Question 2

Coulomb?

Answer 2

The charge of a point with a current of 1 ampere in 1 second

Question 3

Conventional current?

Answer 3

The direction a positive charge carrier would move in a circuit, from the positive terminal to the negative terminal of a power supply.

Question 4

Mean drift velocity?

Answer 4

The average displacement of charge carrying electrons in a circuit towards the negative terminal of the power supply per unit time.

Question 5

Number density?

Answer 5

The number of charge carriers per unit volume.

Question 6

Volt?

Answer 6

1 Joule per Coulomb.

Question 7

Potential difference?

Answer 7

Thhe amount of electrical energy transfered to another energy store per unit charge.

Question 8

Electromotive force?

Answer 8

The amount of energy transfered to electrical energy from another energy store per unit charge.

Question 9

Power?

Answer 9

The rate of energy transfer.

Question 10

Resistance?

Answer 10

The potential difference across a device per the current passing through it.

Question 11

Ohm?

Answer 11

1 volt per ampere.

Question 12

Ohm’s Law?

Answer 12

For a metallic conductor, the current is directly proportional to the potential difference, provided the temperature stays constant.

Question 13

Resistivity?

Answer 13

RA/L, resistivity is measured in Ωm

Question 14

Kilowatt hour?

Answer 14

The energy transferred by a device of 1kW in 1 hour.

Question 15

Kirchhoff’s 1st Law?

Answer 15

The sum of the currents entering a point is equal to the sum of the currents exiting it.
(Conservation of charge).

Question 16

Kirchhoff’s second law?

Answer 16

The sum of the e.m.f in a closed loop of a circuit is equal to the sum of the p.d in the same loop.
(Conservation of energy).

Question 17

Internal resistance?

Answer 17

The resistance of a power source which causes a voltage drop, “lost volts,” when current flows.

Question 18

Progressive wave?

Answer 18

A wave which transfers energy via oscillations, without the transfer of the medium.

Question 19

Transverse wave?

Answer 19

A wave which oscillates perpendicular to the direction of energy transfer.

Question 20

Longitudinal wave?

Answer 20

A wave that oscillates parallel to the direction of energy transfer.

Question 21

Displacement?

Answer 21

The distance of a point above or below the wave’s undisturbed position.

Question 22

Amplitude?

Answer 22

The maximum displacement of a wave from its undisturbed position.

Question 23

Wavelength?

Answer 23

The distance between two consecutive points on two adjacent waves in phase on a progressive wave.

Question 24

Time period?

Answer 24

The time taken for one complete oscillation/ complete wavelength to occur.

Question 25

Frequency?

Answer 25

The number of oscillations/ wavelengths passing a point per unit time.

Question 26

Wave speed?

Answer 26

The distance travelled per unit time.

Question 27

Phase difference?

Answer 27

The angle by which one wave leads or lags another.

Question 28

Reflection?

Answer 28

The change in direction of a wave at the interface between two media back into the original medium.

Question 29

Refraction?

Answer 29

The change in speed, and usually direction, of a wave as it passes from one medium to another.

Question 30

Critical angle?

Answer 30

The angle of incidence of a ray that results in the angle of refraction equalling 90*C

Question 31

Refractive index?

Answer 31

The ratio of the speed of light in a vacuum and the speed of light in a medium.

Question 32

Plane polarisation?

Answer 32

When a transverse wave only has oscillations perpendicular to the direction of energy transfer in one plane.

Question 33

Diffraction?

Answer 33

When a wave spreads out after passing through an aperture or around an obstacle with the same order of magnitude as the wave's wavelength.

Question 34

Intensity?

Answer 34

The radiant power per cross-sectional area. I ∝ A²

Question 35

Principle of superposition?

Answer 35

When two coherent waves interfere, the resultant wave has a displacement the vector sum of the two waves' displacements.

Question 36

Interference?

Answer 36

The superposition of two progressive waves from coherent sources to produce a resultant wave with displacement equal to the vector sum of the two individual displacements of the waves.

Question 37

Coherence?

Answer 37

When two waves have a constant phase difference. Same frequency, polarised in the same plane, similar amplitudes.

Question 38

Path difference?

Answer 38

The difference in the distance between one source and the detector and another source and the detector.

Question 39

Node?

Answer 39

A point of zero amplitude on a standing wave due to destructive interference.

Question 40

Antinode?

Answer 40

A point of maximum amplitude on a standing wave due to constructive interference.

Question 41

Fundamental mode of vibration?

Answer 41

The lowest frequency at which a standing wave can be formed.

Question 42

Harmonics?

Answer 42

Whole number multiples of the fundamental frequency of a stationary wave.

Question 43

Photon?

Answer 43

A quantum of energy of electromagnetic radiation.

Question 44

Electronvolt?

Answer 44

The energy gained when one electron travels through a potential difference of one volt.

Question 45

Photoelectric effect?

Answer 45

The emission of photoelectrons from the surface of a metal when photons are incident with energy greater than the metal's work function.

Question 46

Threshold frequency?

Answer 46

The minimum frequency an electron must oscillate at to escape the surface of a metal.

Question 47

Threshold wavelength?

Answer 47

The maximum wavelength an electron can have to escape the surface of a metal.

Question 48

Work function?

Answer 48

The minimum amount of energy an electron must have to escape the surface of a metal.

Question 49

De Broglie Wavelength?

Answer 49

The ratio of Planck constant to the momentum of the object with a mass.

Question 50

Density?

Answer 50

Mass per unit volume

Question 51

Pressure?

Answer 51

Normal force per cross sectional unit area

Question 52

Archimedes?

Answer 52

For an object fully or partially submerged in a fluid, the upthrust acting on the object is equal to the weight of the fluid displaced.