Static and Current Electricity

Question 1

A polythene rod

Answer 1

Gains electrons if a woollen cloth is rubbed on it (becomes negatively charged)

Question 2

A perspex rod

Answer 2

Loses electrons

Question 3

Unlike charges

Answer 3

Attract each other, like (the same) charges repel each other.

Question 4

Earthing

Answer 4

Occurs when a charged object loses its charge to the earth through a conductor.

Question 5

Static Electricity

Answer 5

Is a build up of electric charge that can occur on good insulators e.g. polythene and perspex.

Question 6

An electric current

Answer 6

Is a flow of electric charge (electrons)

Question 7

Conductors

Answer 7

Are substances which allow electric current to flow through them freely

Question 8

Insulators

Answer 8

Are substances which do not allow electric current to flow through them.

Question 9

Closed circuit

Answer 9

Is needed for the current to flow, if there is a break in a circuit then the current won’t flow

Question 10

Energy provided

Answer 10

By a battery or a power pack, it is needed to move the current around the circuit

Question 11

The battery pumps electrons

Answer 11

From its negative end around a circuit

Question 12

The electrons are attracted

Answer 12

Back to the positive end of the battery

Question 13

Potential difference

Answer 13

The difference in electrical pressure between the positive and negative ends of a battery/power pack

Question 14

Whenever there is a potential difference

Answer 14

Electricity will flow

Question 15

The potential difference is known as

Answer 15

Voltage and is measured

Question 16

Resistance

Answer 16

Is the opposition to the flow of electrons. The unit is the Ohm, and it is measured using an Ohmmeter.

Question 17

If a resistor

Answer 17

Is placed in an electric circuit, it will slow down the flow of electrons.

Question 18

Ohm’s law

Answer 18

Ohm’s law states that voltage is directly proportional to current.

Question 19

DC

Answer 19

Direct current goes in one direction only e.g. the current from a battery.

Question 20

AC

Answer 20

Alternating current changes very quickly, many times a second.

Question 21

Main supply

Answer 21

The mains supply (the electricity in our homes, supplied by the ESB) is A.C. It flows at a potential difference of 230 Volts.

Question 22

The ring circuit

Answer 22

Made of live, neutral and earth wires. Sockets are tapped off at points along this ring circuit

Question 23

Fuse

Answer 23

I’d a safety device that prevents the circuit from overheating. It will melt when it is too hot, breaking the circuit

Question 24

Circuit breaker

Answer 24

Is used in the fuse board of the home, and this trips, to stop the flow of current from entering the house.

Question 25

The live wire

Answer 25

Is brown and carries most electricity it is connected to the fuse on the right hand side

Question 26

The neutral wire

Answer 26

Is blue and it is connected to the left hand side

Question 27

The earth wire

Answer 27

Is a safety wire, no electricity flows in the earth wire unless the appliance it is attached to becomes “live” e.g. A toaster, in this case the earth instead of you electrocuting yourself should you touch the toaster

Question 28

Watt (W)

Answer 28

Is the unit of electrical power

Question 29

The ESB charges a fee for the number of

Answer 29

Kilowatts (1000 watts) used per hour

Question 30

ESB’s unit of electricity is

Answer 30

The kilowatt hour (kWh)

Question 31

A kilowatt hour is

Answer 31

The electrical energy used by a 1kW appliance running for 1 hour

Question 32

Heating effect

Answer 32

Boil water in a kettle, immersion heater, electric cooker, fuse in plug

Question 33

Chemical effect

Answer 33

Electroplating cheap metal with more expensive metal e.g. silver, electrolysis (splitting) of water, mobile phone battery

Question 34

Magnetic effect

Answer 34

Electromagnet made with a wire wrapped around a nail, electric motor, speakers, circuit breaker in fuse board

Question 35

Electronics

Answer 35

Is the careful and exact control of tiny amounts of electric current

Question 36

Diode

Answer 36

Is a component that will allow current to flow in one direction only

Question 37

Forward biased

Answer 37

If the positive end of a battery is connected to the positive end of a diode the diode is said to be “Forward biased” and current can flow

Question 38

Reverse biased

Answer 38

If the positive end of a battery is connected to the negative end of the diode it is said to be “Reverse Biased” and no electricity can flow

Question 39

A diode can be used to

Answer 39

Change alternating current into direct current

Question 40

Electronic devices such as radios, tape recorders and calculators

Answer 40

Need low voltage

Question 41

A light emitting diode

Answer 41

Is a diode that gives out light when a current flows through it.

Question 42

Current will only flow when LED is

Answer 42

Forward biased

Question 43

LED’s use only tiny currents so

Answer 43

A resistor must be connected in series with it

Question 44

LED’s are useful as they are

Answer 44

Cheap, reliable and long lasting and use far less current than other light bulbs

Question 45

A light dependent resistor is

Answer 45

A resistor whose resistance depends on light

Question 46

When light falls on an LDR

Answer 46

It’s resistance decreases, this low resistance will allow a current through the circuit