Electricity

Question 1

Static electricity

Answer 1

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

Question 2

polythene rod

Answer 2

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

Question 3

perspex rod

Answer 3

loses electrons if it is rubbed by a woollen cloth (becomes positively charged)

Question 4

What is an Electric Current

Answer 4

An electric current is caused by the flow of electrons through a good conductor such as a metal

Question 5

Closed circuits

Answer 5

A closed circuit is needed for the current to flow

Question 6

Batteries

Answer 6

• Energy provided by a battery or power packisneededtomovethe current around the circuit
• The battery pumps electrons from its negative end around a circuit
• The electrons travel all the way around and are attracted back to the positive end of the battery

Question 7

High Electrical Pressure

Answer 7

The negative end of the battery is an area of High Electrical Pressure

Question 8

Low Electrical Pressure

Answer 8

The positive end of the battery is an area of Low Electrical Pressure

Question 9

Potential Difference

Answer 9

• The difference in electrical pressure between the positive and negative ends is called the Potential Difference
• Whenever there is a potential difference electricity will flow
• This potential difference is known as Voltage and is measured in volts

Question 10

Resistance

Answer 10

• Resistance is the opposition to the flow of electrons. The unit is the Ohm (Ω), and it is measured using an Ohmmeter
• If a Resistor is placed in an electric circuit, it will slow down the flow of electrons

Question 11

Bulbs in series

Answer 11

• Like the bulb on a christmas tree, what happens if one blows?
• The same amount of current flows through each bulb in the series
• The voltage is split up, depending on the size of the bulb
• If they are the same size bulbs, then the voltage is split evenly

Question 12

Bulbs in parallel

Answer 12

• The lights in your house are connected in parallel, as are car head lights
• If your bedroom light blows, is the kitchen light affected?
• The current is split between the bulbs, if they are the same size, then the current is split evenly
• The same voltage flows through each bulb

Question 13

Direct current

Answer 13

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

Question 14

Alternating Current

Answer 14

• Alternating current changes very quickly, many times a second
• This is how the current is supplied by the ESB
• AC can be converted to DC using a rectifier, smoothed using a capacitor