P10 - P11

Question 1

Difference between series circuit and parallel circuit

Answer 1

In a series circuit there’s only one path for the current to flow , in parallel there’s more than one path for the current to flow .

Same current flows through all components in a series circuit . In parallel current is determined by the split of current flow

In a a series the voltage is the sum of the voltage of the smaller components . voltage is the same in a parallel circuit

Question 2

Describe a Voltmeter and Ammeter

Answer 2

Voltmeter used to measure voltage and connected in parallel

Ammeter used to measure current and connected in series

Question 3

How can we describe a volt ?

Answer 3

1 joule per coulomb

Question 4

Formula for energy transferred ( electrical energy )

Answer 4

Energy transferred = Charge x voltage

E = Q x V

Question 5

Formula for charge

Answer 5

Charge = Current x Time

Q = I x T

Question 6

What happens to current at a junction ?

Answer 6

Current is conserved at a junction in a circuit

Question 7

What is the effect of a Resistor to the current - variable resistor

Answer 7

Inversely proportional to each other

If we increase the current the resistance decreases
If we increase the resistance the current deceases

Question 8

What is he formula for voltage ( ohms law )

Answer 8

Voltage = Current x Resistance
V = I x R

Question 9

Explain what will happen with 2 resistors in a parallel and series

Answer 9

Series : The resistance will add up

Parallel : The resistance will decrease because current increases

Question 10

How does the resistance of an LDR change with light intensity ?

Answer 10

In the dark , the resistance is very high so no current can flow through it

In the bright light , resistance will be low so current will be higher

Question 11

How does a resistance of a thermistor change with temperature ?

Answer 11

At low temperatures , the resistance is high so little current can flow

At high temperatures , the resistance is low so more current can flow

Question 12

What happens when there is an electric current in a resistor - why does this happen

Answer 12

There will be an energy transfer that heats the resistor

this is because of the collusion between electrons and ions

Question 13

How to reduce unwanted energy transfer in a circuit

Answer 13

Use longer and thicker wires

Question 14

Advantages and disadvantages of heat effect in electric current

Answer 14

Reduces lifetime of components in circuit
Cause a fire if too hot

Used in heaters , irons and water heaters
Fuse depends upon detecting heat

Question 15

Formula for energy transferred

4 components

Answer 15

Energy = Current x Voltage x Time 
E = I x V x t

Question 16

What is power and what is the unit

Answer 16

Power is the amount of energy transferred per second

measured in watts (W)

Question 17

What are the 3 equations for power

Answer 17

Power = energy transferred / time

Power = Current squared x resistance

Power = current x potential difference

Question 18

Factors affecting power transfer in a circuit

Answer 18

Potential difference and current

Question 19

Difference between A.c and D.c electricity

Which one does the UK use - watts and Hz

Answer 19

A.c : Direction of current switches at regular intervals

D.c : Direction of current in 1 direction

Cells and batteries supply direct current

UK uses a.c At frequency of 50Hz and 230V

Question 20

What is the function of an earth wire or circuit breaker

Answer 20

This is a safety precaution
earth wire connected to ground to earth
Circuit breaker breaks circuit if there’s a problem

Question 21

What happens if the live wire and the earth wire touch

Answer 21

there would be an electric shock or a fire because there is a 230v difference between them

Question 22

Relationship between power rating and change in stored energy

Answer 22

Higher the power rating , quicker the change in stored energy

Question 23

How can an insulator be charged by friction ?

Answer 23

When 2 insulating materials rub against each other , they will become charged . Electrons will move from 1 insulator to the other so 1 will become positively charged and 1 will become negatively charged

Question 24

Explain lightning and shocks in terms of the electron transfer

Answer 24

Shocks - Someone may become charged for example rubbing socks against a carpet , when this person comes into contact with a normal person thee electrons will go from the charged person to the normal person

Lightening - Clouds move over each other , this causes them to become charged because electrons are transferred between them . The ground is neutral , so the negative charges in the cloud jump to meet the positive charges on the ground , this creates a giant spark

Question 25

How does earthing work ?

Answer 25

Earthing is removing excess charge by moving electrons

Question 26

What are some uses of electrostatic charge

Answer 26

Spraying pesticides - Al the droplets are given the same charge so when they are sprayed out they go away from each other because same charges repel .

Question 27

What are the dangers of filling up a car with fuel

Answer 27

there could be a build up of charge in the pipe because of the fuel rubbing against the pipe , this could cause a spark and cause an explosion

Question 28

What is an electrical field

Answer 28

Region were charges experience a force

Question 29

What is the value of a mA

Answer 29

1/1000 of an amp