Electricity

Question 1

Power (W) equation =

Answer 1

potential difference × current (P = VI)

Current squared x resistance

Question 2

How do you measure voltz

Answer 2

Using a voltmeter

Question 3

How do you measure current

Answer 3

Measured using a ammeter (amps)

Question 4

The amount of energy an appliance transfers depends on what?

Answer 4

how long the appliance is switched on for and the power of the appliance.

Question 5

When is work done

Answer 5

When charge flows in a circuit

Question 6

Eqution for energy transfer

Answer 6

power x time (E = Pt)

charge flow x potential difference (E = QV)

Question 7

How is energy measured

Answer 7

Using a joulmeter or ammeter and voltmeter and stopwatch

Question 8

What is charge flow (Q) measured in

Answer 8

coulombs, C

Question 9

What is voltage (V)

Answer 9

Potential difference (energy transfered) measured using a voltmeter

Question 10

What is the National Grid

Answer 10

The National Grid is a system of cables and transformers linking power stations to consumers. Electrical power is transferred from power stations to consumers using the National Grid.

Question 11

What are step-up transformers used to do

Answer 11

used to increase the potential difference from the power station to the transmission cables

Question 12

What are step-down transformers used to do

Answer 12

step-down transformers are used to decrease, to a much lower value, the potential difference for domestic use.

Question 13

What is resistance

Answer 13

The reduction of flow of electricity measured in ohms

Question 14

How is potential difference is energy transfer per charge passed

Answer 14

When an electrical charge goes through a change in potential energy, then energy is transfered. Energy supplied to the charge at the power to raise is through a potential. The charge gives up this energy when it falls through potential drop in components eleswhere in the circuit.

Question 15

Example of electrical appliances designed to transfer energy to components in the circuit when a current flows

Answer 15

Kettles - they transfer electrically from the mains ac to the thermal energy store of the heating element inside the kettle.
Fan - energy is transfer electrically from the battery to the kinetic energy store of the fan’s motor.

Question 16

How is the National Grid system is an efficient way to transfer energy.

Answer 16

They can predict when the most electicity will be used. Power stations often run at well below their macimum power output and lot of small power stations can start up quickly.

Question 17

How does the narional grid using high pd insted of current make it more efficient

Answer 17

The problem with a high current is that it gives out lots of thermal energy store to the surrounding by wires heating up. Using more pd decreases the amount of current needed

Question 18

How is potential difference changed

Answer 18

Use a transformer

Question 19

How do materials become electically charged

Answer 19

When certain insulating materials are rubbed against each other they become electrically charged.

Question 20

How do electrons move around materials

Answer 20

Negatively charged electrons are rubbed off one material and on to the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with an equal positive charge.

Question 21

What happens when When two electrically charged objects are brought close together

Answer 21

they exert a force on each other. Two objects that carry the same type of charge repel. Two objects that carry different types of charge attract. Attraction and repulsion between two charged objects are examples of non-contact force.

Question 22

How does too much static energy cause sparks

Answer 22

As electircal charge builds up the potential object between the object and the earth increases. If the pd is large enough, electron can jumo across the gap between the charge objects and earth creating a spark. They can also jump to any earthed conductor

Question 23

How are materials electrically charged

Answer 23

When electrons transfer leaving a posotiv pe static charge and an eqaul negative charge on the other

Question 24

What does A charged object create around it

Answer 24

an electric field (The electric field is strongest close to the charged object)

Question 25

How is the force effected by distance when A second charged object placed in a field

Answer 25

The force gets stronger as the distance between the objects decreases.

Question 26

How are forces caused in electrical fields

Answer 26

They are the forces of attraction or repulsion from charged objects interacting.

Question 27

What should should be mentionedin exam when toled to explain motion

Answer 27

Either the moition:
Acceleration
Decceleration
Staying constant
Stationary