Topic 10

Question 1

10.1
Describe the structure of an atom

Answer 1

-Mass conc in middle
-Nuc: + proton & neutral neutron
-Negative e^- orbit nuc in energy levels

Question 2

10.3
State the difference between a series and parallel circuit

Answer 2

-S: 1 complete loop
-P: 2 or more loops connected together

Question 3

10.5
Define the term voltage

Answer 3

How much I flows

Question 4

10.5
Define the term potential difference

Answer 4

E transferred per unit charge

Question 5

10.5
State the unit used to measure potential difference & another unit that means the same thing

Answer 5

-Volts (V)
-Joule per coulomb

Question 6

10.6
State the equation for energy transferred, charge and voltage. Include units

Answer 6

-E=Q×V
(Energy=Charge×p.d)
-E=J
-Q=C
-p.d=V

Question 7

10.8
a) Define the term current
b) How does current flow in metals?

Answer 7

a) Rate of flow of charge
b) Flowing electrons

Question 8

10.8
State 2 ways the current in a metal can be increased

Answer 8

-Increase V
-Decrease R

(Increase no. of e^-?)

Question 9

10.9
State the equation for charge. Include units

Answer 9

-Q=It
(Charge=Current × time)
-Q=C
-I=A
-t=s

Question 10

10.10
What happens in a closed circuit when there is potential difference?

Answer 10

There will be current

Question 11

10.11
Compare the movement of current in a series and parallel circuit

Answer 11

-S: Constant everywhere
-P: Splits between loops (conserved at junctions)

Question 12

10.11
Compare the movement of potential difference in a series and parallel circuit

Answer 12

-S: Splits between components
-P: Constant on each branch

Question 13

10.12
Explain the effect of increasing the resistance in a circuit on the current

Answer 13

-e^- collide w/ +ions more -> slow down
-Decreases I

Question 14

10.12
Compare a fixed and variable resistor

Answer 14

Fixed
-Has constant value
-Therefore provides constant resistance
Variable
-No fixed value (change as I changes)

Question 15

10.12
What will components in a circuit act as? Why?

Answer 15

-Variable resistors
-R depends on I flowing through them

Question 16

10.12
Define the term resistance

Answer 16

How difficult it is for I to flow

Question 17

10.13
State the equation for voltage. Include units

Answer 17

-V=IR
(p.d=current/resistance)
-V=V
-I=A
-R=Ω (ohms)

Question 18

10.14
Explain whether resistors in series or parallel would have a higher resistance

Answer 18

-Series
-Only 1 path e^- can flow through
-P= e^- have 2 paths

Question 19

10.15
In a series circuit, the current is 10A and the voltage comes from a mains supply, calculate the resistance

Answer 19

-V=IR
-230=10×R
-R=230/10
-R=23Ω

Question 20

10.16
Suggest 2 disadvantages of using a series circuit rather than a parallel circuit

Answer 20

-1 component breaks -> whole circuit breaks
-Components can’t be controlled separately

Question 21

10.17
When devising an experiment with current, what voltage should you not exceed?

Answer 21

15V

Question 22

10.18
Explain what a diode is and how it works

Answer 22

a) -Component
-Allows I to pass
-In only 1 direc
b) -Has more R in 1 direc than the other

Question 23

10.19
Describe how an LDR works
(What does LDR stand for?)

Answer 23

-Light-dependent resistor
-Light intensity ↑ -> R ↓ -> ↑ I flows

Question 24

10.20
Describe how a thermistor works

Answer 24

-R depends on temp
-↑ temp= ↓ R -> ↑ I flows thru

Question 25

10.21 10.16 Explain how the *variation* of resistance can be measured for any component e.g. a lamp

Answer 25

Circuit w/... -Battery -Ammeter -Variable resistor -Tested component -Voltmeter in parallel to component (Note: To test fixed R, don't need variable resistor)

Question 26

10.16 Devise an experiment to measure the resistance of an a) LDR b) Thermistor

Answer 26

a) Circuit w/ -Battery -LDR -Voltmeter parallel to LDR -Ammeter Vary light intensity & take readings b) Same thing but w/ varying temps instead

Question 27

10.22 10.23 10.24 Explain the energy transfer that is caused by resistance

Answer 27

-↑ collisions between e^- & +ions in metal -> ions vibrate ↑ -Electrical E transferred to thermal -Thermal further ↑ R -Dissipated to surroundings (resistance causes heat)

Question 28

10.25 Describe the effect of heating on resistance

Answer 28

-Gain KE -Ions vibrate more -> collide more w/ e^- -Harder for e^- to flow -R increases

Question 29

10.25 How can unwanted energy transfers be reduced within a wire?

Answer 29

-Use low resistance wires -↓ collisions -> ↓ vibrations -> ↓ thermal energy dissipated

Question 30

10.26 Evaluate the advantages and disadvantages of the heating effect of an electric current

Answer 30

Adv: -Heat could be useful Dis: -E loss -Risk of fire? -Could overheat -> damage

Question 31

10.27 State the equation for energy transferred, voltage, current and time. Include units

Answer 31

E=V×I×t (Energy=current×p.d×time) -E=J -V=V -I=A -t=s

Question 32

10.28 Define the term power. State the units

Answer 32

-r. E transferred per second -Watts (W)

Question 33

10.30 Explain how the power transfer in any circuit device is related to the potential difference & current

Answer 33

-As p.d ↑ P ↑ -As I ↑ P↑ (P=IV)

Question 34

10.29 10.31 a) State 3 equations used to find power. Include units b) How do you know when to use each

Answer 34

a) -P=E/t -P=I×V -P=I²×R Units -P=W -E=J -t=s -I=A -V=V -R=Ω b) -P=IV when power SUPPLIED -P=I²R when power DISSIPATED

Question 35

10.32 Describe how energy is transferred from batteries to the energy of motors and heating devices

Answer 35

-Batteries store d.c. & release -Convert chemical-> electrical E

Question 36

10.32 Describe how energy is transferred from a.c. mains to the energy of motors and heating devices

Answer 36

-Supply a.c. -Transformers step up/down V from mains to match requirement of devices

Question 37

10.33 10.34 10.35 Compare direct & alternating voltage

Answer 37

Direct -p.d (charge movement - same thing) 1 direc -Produced by batteries & cells (when plugged in, only stays in 1 direc) Alternating -p.d CHANGES direc -Produced by generators Diagrams https://www.ecosia.org/images?q=alternating%20and%20direct%20current%20graph&addon=opensearch#id=46845DFD76A753BEF8B469192FE81563822A1368

Question 38

10.36 State 3 features about mains electricity in the UK

Answer 38

-Alternating current -Voltage = 230V -Frequency = 50Hz

Question 39

10.36 Explain why alternating current is better for domestic use

Answer 39

Transferred over long d efficiently

Question 40

10.36 What does a frequency of 50Hz mean?

Answer 40

I changes direc 50 times per second

Question 41

10.37 Describe the function of a neutral wire in plugs

Answer 41

-Provides return route -For I to flow back -To power station

Question 42

10.37 Describe the function of a live wire in plugs

Answer 42

-I flows thru wire -To required parts of appliance -Maintains p.d of 230V

Question 43

10.38 10.39 Describe the function of an earth wire in plugs. Explain why it should be connected to the live wire

Answer 43

-Connects metal part of circuit to metal spike in ground (in case live wire detaches & touches metal) -p.d of 0V = device functioning well

Question 44

10.38 10.39 Describe the function of a fuse in plugs

Answer 44

-Has wire that melts if I raises above fuse rating -Breaks circuit (Extra: If appliance draws too much current -Affects R -> affects thermal energy produced -> potential fire)

Question 45

10.40 State the potential difference of... a) Earth b) Live c) Neutral

Answer 45

a) 0V b) 230V c) 0V

Question 46

10.41 Explain 2 dangers of providing a connection between the live and earth wire (electricity)

Answer 46

Fire -e^- collide w/ +ions -> vibrate -> transfer electrical energy to thermal -> dissipates heat. -Too many devices close together = fire Electric shock -Insulator around wires tears/breaks -> exposed wires

Question 47

State 4 factors that affect resistance

Answer 47

-Material -Length of wire (longer = ↑ R) (Proportional) -Cross section A (↑ A = ↓ R) (Inversely) -Temp (↑ temp = ↑ R) (Proportional)

Question 48

1 Watt is the same as ...

Answer 48

1 J/s

Question 49

10.42 Use an example to describe the relationship between the power ratings of domestic electrical appliances and the energy consumed.

Answer 49

-Domestic appliances w/ ↑ P ratings consume ↑ E (directly ∝) -Kettle w/ ↑ P rating heats water faster than kettle w/ ↓ P rating

Question 50

What does LED stand for and how does it work?

Answer 50

-Light emitting diode -**Semiconductor**: I flows -> emits light

Question 51

Reminder to do physical cards too