Electricity

Question 1

What is a current

Answer 1

A measure of the flow of electrons around a circuit (amps)

Question 2

What is Potential difference

Answer 2

It is the force driving the flow of electrons (voltage)

Question 3

What is a circuit

Answer 3

Closed loop

Question 4

What is Resitance

Answer 4

Everything that resists or opposes the flow of electrons

Question 5

Which way does current flow in a circuit

Answer 5

From positive to negative

Question 6

Potential difference/Voltage (V) =

Answer 6

Current (A) x Resistance (Ohms)

Question 7

Why does a filament lamps Voltage and current graph bend

Answer 7

High temp = High resistance

Question 8

What is a diode

Answer 8

Has very high resistance in one direction and very little in another

Question 9

Example of directly proportional in electricity

Answer 9

When resistance stays the same, Voltage is directly Proportional to Current

Question 10

What is always the same in a series circuit

Answer 10

Current is always the same

Question 11

What is a series circuit

Answer 11

A electrical circuit with only one loop

Question 12

What is a parallel circuit

Answer 12

a electrical circuit with more than one loop

Question 13

What happens when a single part stops working or breaks in a series circuit

Answer 13

it will stop working

Question 14

In a series circuit, what happens with the voltage/potential difference

Answer 14

It is shared with all components, (So if two of the same lamps and battery voltage is 12V, both will have 6V)

Question 15

In a parallel circuit what happens to the PD/voltage

Answer 15

All components get all of the voltage

Question 16

In a parallel circuit what happens to the current

Answer 16

shared between components (12A = 5A + 7A)

Question 17

In a parallel circuit what happens to the Resistance

Answer 17

More components in the circuit the less the resistance (More choices or pathway)

Question 18

What is AC

Answer 18

Alternating current is when we use an alternating voltage which swaps back and forward. 230/240 V and 50Hz

Question 18

What is DC

Answer 18

Stays either + or -, Used for phones or calculators

Question 19

What are Oscilloscopes

Answer 19

Make potential difference/time graphs

Question 20

What do cells provide electrons

Answer 20

energy

Question 21

What store of energy do cells have

Answer 21

Chemical potential energy

Question 22

What is electro-magnetism

Answer 22

When an electrical current forms its own magnetic field

Question 23

What are 4 ways we can increase the strength of an electro magnet

Answer 23

More current
More turns in coil
Less coil with same turns
Iron core

Question 24

Why can’t the national grid have a high current, and what does it do instead?

Answer 24

High current would cause the temperature to increase to high amounts, meaning that it would heat up, instead we increase the voltage to large amounts

Question 25

How does the national grid work

Answer 25

Power stations produce energy through fission or other, this energy goes through step up transformers which increases the voltage, this is then transported to houses where step down transformers decrease the voltage so that the electricity can be used.

Question 26

How does a fuse work

Answer 26

made of thin wire
* fuse connected between live pin and wire to kettle
* temperature of wire depends on current in it
* when the current is (very) large, the temperature
of the wire increases beyond melting point of wire
* fuse (wire) breaks
* disconnects mains supply to kettle
* prevents damage to house wiring
* (now) there is no possibility of live wire in kettle
being at mains voltage

Question 27

How does the earth wire work

Answer 27

earth wire connected to metal case
* metal case is a conductor
* (when live touches case) resistance between live
and earth is very low
* (very) large current to earth through (low
resistance) earth wire
* case is kept at same potential as earth
* so cannot get a shock if (earthed) person touches
metal case