Electricity

Question 1

What is ohm’s law?

Answer 1

voltage = current x resistance

Question 2

If we increase the resistance of a component, what happens to the current flowing through it?

Answer 2

It decreases.

Question 3

What is a series circuit?

Answer 3

A circuit with all components connected one after another, in one path.

Question 4

What is a parallel circuit?

Answer 4

A circuit with the components connected in different branches, there is more than one path around the circuit.

Question 5

What is a battery?

Answer 5

Two or more cells

Question 6

What does an ammeter measure?

Answer 6

Current in Amps (A). They are connected in series.

Question 7

What does a voltmeter measure?

Answer 7

Potential Difference or Voltage in Volts (V). They are always connected in parallel.

Question 8

What colour is the live wire?

Answer 8

Brown

Question 9

What colour is the earth wire?

Answer 9

Green and yellow striped

Question 10

What colour is the neutral wire?

Answer 10

Blue

Question 11

Which wire is connected to the fuse?

Answer 11

Live (brown one)

Question 12

Which side of the plug does the live wire go?

Answer 12

Right (bRown - Right)

Question 13

Which side of the plug does the neutral wire go?

Answer 13

Left (bLue - Left)

Question 14

What material (and why??) is the plug casing made of?

Answer 14

Plastic - because it is an insulator

Question 15

What material (and why??) is the inside of the wire made of?

Answer 15

Metal (copper) because it is a conductor

Question 16

What is the voltage of UK mains?

Answer 16

230V

Question 17

What is the frequency of UK mains?

Answer 17

50Hz

Question 18

What does the horizontal (x-axis) show on an oscilliscope trace?

Answer 18

Time

Question 19

What does the vertical (y-axis) show on an oscilliscope trace?

Answer 19

Voltage

Question 20

What is inside a fuse?

Answer 20

A thin wire which melts if the current is too high

Question 21

Why do some appliances not need an earth wire?

Answer 21

They are double insulated

Question 22

The resistance in a thermistor increases as?..

Answer 22

…temperature decreases.

Question 23

The resistance in an LDR increaes as?

Answer 23

?light intensity decreases.

Question 24

To find the total resistance of two resistors in series we?.

Answer 24

?add them.

Question 25

What does a DC supply look like on an oscilliscope trace?

Answer 25

A straight horizontal line

Question 26

What is this component and what does it do?

Answer 26

It is an ammeter, it measures current in Amps (A)

Question 27

For what is this the symbol? What does the component do?

Answer 27

It is a battery. A battery is more than one cell - it delivers energy to the circuit. The total voltage of the battery is the sum of all the cells

Question 28

What is this the symbol for and what does it do?

Answer 28

A cell. It delivers energy to the circuit.

Question 29

What component is this the symbol for and what does it do?

Answer 29

Diode It allows the current to flow in one direction only (the direction the arrow is pointing).

Question 30

What component is this the symbol for and what does it do?

Answer 30

A fuse It melts and breaks the circuit if too large a current flows through it.

Question 31

What component is this the symbol for and what does it do?

Answer 31

A lamp. It converts electrical energy to light (useful) and heat (wasted).

Question 32

What component is this the symbol for and what does it do?

Answer 32

A Light Dependent Resistor (LDR) Its resistance alters depending upon the brightness of the light falling on it. The brighter the light, the lower the resistance.

Question 33

What component is this the symbol for and what does it do?

Answer 33

A Light Emitting Diode (LED) Like a diode, it will only let current flow in one direction (the direction of the arrow). It indicated that a current is flowing with a small light - e.g. a 'power on' light

Question 34

What component is this the symbol for and what does it do?

Answer 34

A resistor It controls the amount of current in a circuit (for a fixed voltage).

Question 35

What component is this the symbol for and what does it do?

Answer 35

A Thermistor It is a resistor that changes resistance depending on temperature. High temperatures mean a lower resistance.

Question 36

What component is this the symbol for and what does it do?

Answer 36

A Variable resistor. These are resistors that can change their resistance. They can be used to control a current in a circuit e.g. a dimmer switch or volume control

Question 37

What component is this the symbol for and what does it do?

Answer 37

A Voltmeter This measures the Potential Difference (P.d. or Voltage) between two points in a circuit. They are connected in parallel.

Question 38

This is the current voltage graph for a ....

Answer 38

Filament lamp. As it's temperature increases, the resistance increases because the electrons find it more difficuklt to move past atoms that are vibrating more rapidly.

Question 39

This is a current voltage graph for a .....

Answer 39

Straight wire at constant temperature. The voltage is proportional to the current

Question 40

This is a current voltage graph for a .....

Answer 40

Diode Current can flow in one direction only

Question 41

What is current?

Answer 41

Current is the flow of charge (electrons) around a circuit. It alwas flows from the positive (long) side of a cell or battery to negative (short)

Question 42

What is the symbol for current

Answer 42

I

Question 43

Two insulators are rubbed together and create static electricity. How does this happen.

Answer 43

The friction between the two insulators rubs electrons off one onto the other

Question 44

Two insulators are rubbed together and become charged. Explain why one is negative and one positive

Answer 44

Negative electrons have moved. The insulator that is negative has gained electrons. The insulator that is positive hads lost electrons.

Question 45

Similar charges ....

Answer 45

repel.

Question 46

Opposite charges ....

Answer 46

attract.

Question 47

A charged object will discharge if ...

Answer 47

it is Earthed

Question 48

An 'Earthed' object has..

Answer 48

a conducting (metal) path to the ground.