Section 6 - Electricity

Question 1

Current def

Answer 1

Rate of flow of charge

Question 2

I, Q, T formula

Answer 2

Q = It

Question 3

Direction of current flow

Answer 3

+ to -

Question 4

Unit of charge

Answer 4

Coulomb (C)

Question 5

Coulomb def

Answer 5

One coulomb is the amount of Charge that passes in 1 second if the charge is 1 Amp

Question 6

Potential Difference def

Answer 6

Work done per unit charge moved

Question 7

Voltage f

Answer 7

v = W/Q (Word done/charge)

Question 8

Voltage in components connected in a parallel

Answer 8

The same

Question 9

Current in components connected in a parallel

Answer 9

Shared

Question 10

Voltage in components conected in series

Answer 10

Shared

Question 11

Current in components connected in seres

Answer 11

The same

Question 12

How must a voltmeter be connected

Answer 12

in parallel with the component

Question 13

Definition of a volt

Answer 13

1 volt is when you convert 1 joule of energy moving 1 coulomb of charge through a component

Question 14

Resistance f

Answer 14

R = V/I

Question 15

Resistance def

Answer 15

A measure of how difficult it is for current to flow through a component

Question 16

Ohmic conductor def

Answer 16

A conductor for which |R is constant

Question 17

Ohms law

Answer 17

Provided the physical conditions, such as temperature, remain constant, the current through an ohmic conductor is directly proportional to the current across it

Question 18

Graph for an ohmic conductor

Answer 18

Straight line graph passing through (0,0)

Question 19

Circuit to obtain an I/V graph

Answer 19

INsert pic

Question 20

I/V graph for a filament lamp

Answer 20

INsert pic

Question 21

I/V characteristic for a filament lamp

Answer 21

The resistance of a metal increases as the temperature increases

Question 22

Semiconductors

Question 23

Thermistor def

Answer 23

A resistor with a resistance that depends on temperature

Question 24

NTC thermistor

Answer 24

Negative temperature coefficient
Resistance decreases as temperature goes up

Question 25

Filament lamp symbol

Answer 25

Pic

Question 26

Thermistor symbol

Answer 26

Pic

Question 27

NTC thermistor I/V graph

Answer 27

Pic

Question 28

How a NTC thermistor works

Answer 28

Warming the thermistor gives more electrons enough energy to escape from their atoms, this means that there are more charge carriers available so the resistance is lower`

Question 29

Diodes def

Answer 29

Components that only allow current to flow in one direction

Question 30

Diode Symbol

Answer 30

Pic

Question 31

LED symbol

Answer 31

Pic

Question 32

Forward bias def

Answer 32

The direction in which a diode allows current to flow

Question 33

Three things that determine resistance

Answer 33

- Length of wire (l) - Cross sectional area of a wire (A) - Resistivity ((P))

Question 34

Resistivity def

Answer 34

The resistivity of a material is defined as the resistance of a 1m length with corss sectional area 1m^2

Question 35

Resistivity units

Answer 35

Ohm-metres`

Question 36

Resistivity formula

Answer 36

RA/l

Question 37

Experiment to find the resistivity of a wire

Question 38

Superconductors def

Answer 38

Materials with zero resistance

Question 39

Power def

Answer 39

The rate of transfer of energy

Question 40

Unit of power + def

Answer 40

Watts: 1 joule per second

Question 41

Power formla

Answer 41

P = E/t

Question 42

3 formulae for power in a electrical circuit

Answer 42

P = VI P = (v^2)/R P = (I^2)R

Question 43

What causes resistance

Answer 43

Resistance comes from electrons colliding with atoms and losing energy to other forms

Question 44

Internal resistance def

Answer 44

The resistance to the flow of charge within a power source such as a battery

Question 45

Load resistance

Answer 45

The total resistance of all components in the external circuit

Question 46

EMF def

Answer 46

The amount of electrical energy the battery produces for each collumb of chargeE

Question 47

EMF full form

Answer 47

Electromotive Force

Question 48

EMF unit

Answer 48

VOlts

Question 49

EMF formula

Answer 49

EMF = E/Q

Question 50

Terminal PD def

Answer 50

The potential difference across the load resistance, the energy transferred when one coulomb f charge flows through the load resistance

Question 51

What would happen if there was no internal resistance

Answer 51

The terminal PD would be the same as the EMF

Question 52

Lost volts def

Answer 52

The energy wasted per coulomb overcoming the internal resistance

Question 53

Conservation energy

Answer 53

Energy per coulomb supplied by the source = Energy per coulomb transferred in load resistance + Energy per coulomb wasted in internal resistance

Question 54

4 formulae with EMF and internal resistance

Answer 54

Pic

Question 55

EMF of cells in series

Answer 55

Et = E1 + E2 +E3 ...

Question 56

EMF of cells in parallel

Answer 56

Et = E1 = E2 = E3 ...

Question 57

Investigating Internal resistance and EMF circuit

Answer 57

Pic

Question 58

Investigating internal resistance and EMF steps [3]

Answer 58

- Vary the current in the circuit by changing the vaue of theload resistance(using the variable resistor). - Measure the PD for several values of current - Record the results and plot a graph of v against I

Question 59

Calculating internal resistance and MEF from a V-I graph

Answer 59

Pic

Question 60

Kirchhoff's fist law

Answer 60

Conservation of charge The total current entering a junction = the total current leaving it

Question 61

Kirchhoff's second law

Answer 61

Conservation of energy The total EMF around a series circuit = the sum of the PDs across each component

Question 62

Adding resistance in series

Answer 62

Rt = R1 + R2 +R3 ...

Question 63

Deriving how resistance is added in series

Answer 63

Pic

Question 64

Adding resistance in Parallel

Answer 64

1/Rt = 1/R1 + 1/R2 + 1/R3 ...

Question 65

Deriving how resistance is added in series

Answer 65

Pic