Module 2 definitions

Question 1

Electric current

Answer 1

The rate of flow of charge

Question 2

Quantised

Answer 2

The availability of some quantities such as energy or charge

Question 3

Conventional current

Answer 3

Conventional current travel from positive to negative- it is the direction in which positive charge would travel

Question 4

Conservation of charge

Answer 4

Electric charge cannot be created or destroyed. The total charge for any interaction must be the same before and after.

Question 5

Kirchhoff first law

Answer 5

At any point in an electrical circuit, the sum of current into that point is equal to the sum of currents out of that point, electrical charge is conserved.

Question 6

Number density

Answer 6

The number of free electrons per cubic metre of a material

Question 7

Semiconductor

Answer 7

A material with a lower number density than a typical conductor eg silicon

Question 8

Mean drift velocity

Answer 8

The average velocity of electrons as they move through a wire.

Question 9

Potential difference

Answer 9

The energy transferred from electrical energy to other forms (heat light) per unit charge.

Question 10

Electromotive force

Answer 10

The energy transferred from chemical to electrical energy per unit charge.

Question 11

Ohm’s law

Answer 11

The potential difference across a conductor us directly proportional to the current in the component as long as its temperature remains constant

Question 12

Ohmic conductor

Answer 12

A conductor that obeys ohms law

Question 13

Diode

Answer 13

a semiconductor that allows current only in one particular direction

Question 14

Threshold pd

Answer 14

The minimum potential difference at which a diode begins to conduct

Question 15

Resistivity

Answer 15

A property of material
The product of the resistance of a component made of that material and its cross sectional area divide by its length.

Question 16

Kilowatt hour

Question 17

Kirchhoff second law

Answer 17

In a close loop of an electrical circuit the sum of emf is equal to the sim of pds

Question 18

Lost volts

Answer 18

The potential difference across the internal resistor of a source of emf

Question 19

m

Question 20

Terminal pd

Answer 20

The potential difference across a electrical power source- when there is no current this is equal to the emf of the source but if there is current the source is equal to the emf minus the lost volts.

Question 21

Potential dividers

Answer 21

An electrical circuit designed to divide the potential difference across two or more components in order to produce a specific output.

Question 22

Longitudinal waves

Answer 22

Oscillations are parallel to the direction of the wave travel

Question 23

Equilibrium position

Answer 23

The resting position if waves or particles in an oscillation

Question 24

Wavelength

Answer 24

The minimum direction between two points oscillating in phase.

Question 25

Wave speed

Answer 25

The distance travelled by the wave per unit time.

Question 26

Time period

Question 27

Phase difference

Answer 27

The difference between the displacement of particles along a wave same or different waves.

Question 28

Reflection

Answer 28

The change in direction of a wave at a boundary between two different media, so that the wave remains in the original medium

Question 29

Refraction

Answer 29

The change in direction of a wave as it changes speed when it passes from one medium to another

Question 30

Law of reflection

Answer 30

The angle of incidence is equal to the angle of reflection

Question 31

Diffraction

Answer 31

The phenomenon waves passing through a gap or around an obstacle spread out.

Question 32

Polarisation

Answer 32

The phenomenon in which the oscillation of a transverse wave are limited to only one plane.

Question 33

Intensity

Answer 33

The radiant power passing through a surface per unit area.

Question 34

Refractive index

Question 35

Total internal reflection

Answer 35

The reflection of all light hitting a boundary between two media back into the original medium when light is travelling the medium with the higher refractive index and the incidence angle at the boundary is greater than the critical angle.

Question 36

Critical angle

Answer 36

The angle of incidence at the boundary between two media that will produce an angle of refraction of 90degrees.

Question 37

Interference

Answer 37

Superposition of two progressive waves from coherent sources to produce a resultant wave with the displacement equal to the sum of individual displacement from the two waves

Question 38

Principle of superposition

Answer 38

When two similar waves meet at a point the resultant displacement at that point is equal to the sum of the displacement of the individual waves.

Question 39

Constructive interference

Answer 39

Superposition of two waves in phase so that the resultant wave has a greater amplitude than the original waves.

Question 40

Destructive interference

Answer 40

Superposition of two waves in anti phase so that the waves cancel each other out and the resultant waves has smaller amplitude than the original wave

Question 41

Path difference

Answer 41

The difference in the distance travelled by two waves from their source to a specific point.

Question 42

Monochromatic

Answer 42

Light of a single frequency.

Question 43

Node

Answer 43

For a stationary wave a point where the amplitude is always zero.

Question 44

Antinode

Question 45

Stationary wave

Answer 45

A wave that remains in a constant position with no net transfer of energy and is characterised but its nodes and antinodes.

Question 46

Fundamental frequency

Answer 46

The lowest frequency at which an object can vibrate.

Question 47

Photons

Answer 47

A quantum of electromagnetic energy

Question 48

Electronvolt

Answer 48

The energy transferred to or from an electron when its passes through a potential difference of 1 volt.

Question 49

Photoelectric effect

Answer 49

The emission of photoelectrons from a metal surface when electromagnetic radiation above the threshold frequency is incident on the metal.

Question 50

Threshold frequency

Answer 50

The minimum frequency of the electromagnetic radiation that will cause the emission of an electron from the surface of a particular metal.

Question 51

Work function

Answer 51

The minimum energy needed to remove a single electron from the surface of a particular metal.

Question 52

Photoelectrons

Answer 52

Electron emitted from the surface of a metal by the photoelectric effect

Question 53

Wave particles duality

Answer 53

A theory that states that material has both particle and wave properties and electromagnetic radiation has both wave and photon nature.