Electricity Part 2

Question 1

The resistance of a light dependant resistor decreases…

Answer 1

As light intensity increases

Question 2

The resistance of a thermistor decreases…

Answer 2

As the temperature increases

Question 3

What is the forward resistance for a diode like?

Answer 3

Low resistance so reverse resistance is high so there is negligible current in the reverse direction

Question 4

What happened to the resistance of a LDR as light intensity increases?

Answer 4

Resistance of the LDR decreases at light intensity increases

Question 5

What happens to the resistance of a thermistor as the temperature increases?

Answer 5

The resistance of the thermistor decreases as the temperature increases

Question 6

What is the current through each component for a component connected in series?

Answer 6

The current through each component is the same for components connected in series

Question 7

How can you calculate the total potential difference of components in series?

Answer 7

Adding the potential differences of each component gives the total PD

Question 8

What is the total resistance of components connected in series?

Answer 8

The sum of the resistance of each component

Question 9

What is the total current of component connected in parallel?

Answer 9

The sum of the currents through the separate components

Question 10

What is the potential difference of each component in parallel?

Answer 10

The potential difference across each component is the same

Question 11

For components connected in parallel the bigger the resistance ……………

Answer 11

The smaller the current

Question 12

How can you calculate the current through a resistor in parallel?

Answer 12

Using the equation I= V/R

Question 13

What is direct current?

Answer 13

Current that travels in one direction only

Question 14

What is alternating current?

Answer 14

Current that repeatedly reverses

Question 15

What is the peak voltage of an alternating potential difference?

Answer 15

The maximum voltage measured from zero volts

Question 16

What Dee’s the live wire alternate between?

Answer 16

Alternates between positive and negative every cycle

Question 17

What voltage is the neutral wire at?

Answer 17

Zero volts

Question 18

In the uk what does the voltage alternate between?

Answer 18

325 and -325V

Question 19

What is 325 and -325 in alternating current equal to in direct current?

Answer 19

230 in direct voltage

Question 20

How can you measure the frequency of an a.c supply?

Answer 20

Measure the time period of the waves and then use the formula frequency = 1/time taken for one cycle

Question 21

In the uk what is the mains supply frequency?

Answer 21

50Hz

Question 22

What are sockets and plugs made of? And why?

Answer 22

They are made of stiff plastic that enclose the electrical connections
Plastic is used as it is a good electrical insulator

Question 23

An appliance with a plastic case is said to be …………. …………….

Answer 23

Doug,y insulated

Question 24

What do mains cables consist of?

Answer 24

2 or 3 insulated copper wires surrounded by an outer layer of flexible plastic material

Question 25

What colour is the live wire?

Answer 25

Brown

Question 26

What colour is the neutral wire?

Answer 26

Blue

Question 27

What colour is the earth wire?

Answer 27

Green and yellow

Question 28

Which pin is the earth wire connected to?

Answer 28

The longest pin

Question 29

What is the earth wire used for?

Answer 29

It is used to earth the metal case of a mains appliance

Question 30

What is a fuse?

Answer 30

A thin wire that heats up and melts cutting of the current if the current is too large

Question 31

How is a fuse fitted?

Answer 31

It is fitted in series with the live wire so if the fuse blows ipthe current from the live wither is cut off

Question 32

What is a circuit breaker?

Answer 32

An electromagnetic switch that opens and cuts off the current in the live wire if too much current passes through the circuit breaker

Question 33

Why is a circuit breaker better than a fuse?

Answer 33

It works faster | Can be reset quickly

Question 34

What does RCCB stand for?

Answer 34

Residual current circuit breaker

Question 35

What does a RCCB do?

Answer 35

Cuts off the current in the live wire if it is different from the current in the neutral wire

Question 36

What is the benefit of RCCB?

Answer 36

It is more sensitive than both a fuse and a circuit breaker

Question 37

Why does a mains appliance with a plastic case not need to be earthed?

Answer 37

Plastic is an insulator and cannot become live

Question 38

Why should appliances with metal cases be earthed?

Answer 38

So that if a fault occurs the metal case is safe to touch

Question 39

What is power?

Answer 39

The energy transferred to an appliance each second

Question 40

When an electrical charge through a resistor ........... ............ To the resistor makes it .....

Answer 40

Energy Transferred Hot

Question 41

When a ....... Flows round a circuit for a certain time the ........... Energy supplies by the battery is ........... To the electrical energy transferred to ..... Components in the circuit

Answer 41

Charge Electrical Equal All

Question 42

Why are electrical faults dangerous?

Answer 42

They can cause electric shocks and fires

Question 43

What should you consider when choosing an appliance?

Answer 43

Power and efficiency

Question 44

Filament bulbs and halogen bulbs are much ....... Efficient than ..... Energy bulbs

Answer 44

Less | Low

Question 45

You should tough a mains appliance or plug or wicket with ..... ...... And should never touch a bare wire or terminal at a potential of more than ......

Answer 45

Wet hands | 30V