E&E

Question 1

What happens to voltage in a series circuit?

Answer 1

It’s is shared between the components

Question 2

Formula for Vs

Answer 2

Vs=V1+V2

Question 3

What happens to current in a series circuit ?

Answer 3

It is the same at every point

Question 4

The resistance of an electrical component is defined as:

Answer 4

The voltage across it divided by the current through it

Question 5

Three parts of electronic system

Answer 5

INPUT-PROCESS-OUTPUT

Question 6

What does the input device do ?

Answer 6

The input device changes one from of energy to electrical energy.

Question 7

Example of input devices

Answer 7

Two examples of INPUT devices are solar cells (light) and thermistors (temperature change).

Question 8

What does the process device do ?

Answer 8

The process device then does something to the electrical signal e.g. an amplifier makes it larger.

Question 9

What does the output device do ?

Answer 9

Next, the output device converts the processed electrical signal into another form of energy e.g. an LED produces light.

Question 10

How does an and gate activate an output ?

Answer 10

For an AND gate to activate an output, both inputs musts be on.

Question 11

How does an or gate activate and output ?

Answer 11

For an OR gate to switch on the output device, either input can be on.
For example, to switch on a car interior lamp if a passenger OR the driver opens a door then you would have switches (inputs) on each door and an OR Gate to turn on the lamp.

Question 12

Electricity generation

Answer 12

Electricity is generated in a variety of ways. There are two main categories for generating electricity: non-renewable and renewable energy resources.

Question 13

Non renewable energy resources

Answer 13

Most non-renewable energy resources use fossil fuels (coal, oil and natural gas) to generate electricity. In fossil fuel generators, the chemical energy of the fuel is burned to release heat energy.

Question 14

What are magnets attracted to ?

Answer 14

• Magnets are attracted to certain metals, e.g. iron and steel.
• The ends of a magnet are called the North and South poles.

Question 15

What is used to show the magnetic field around a magnet ?

Answer 15

• Iron filings can be used to show the magnetic field around a magnet.
• Magnetic field lines have arrows on which point from North towards South.

Question 16

What produces a magnetic field

Answer 16

• A wire with a current flowing in it produces a magnetic field.

Question 17

How is an electromagnet made ?

Answer 17

• An electromagnet can be made by winding insulated wire around an iron core and passing current through the wire.

Question 18

What is a transformer?

Answer 18

• A transformer consists of two coils wound around the same iron core.

Question 19

What do transformers do?

Answer 19

• Transformers use a.c. (alternating current) in the primary coil to create a constantly changing magnetic field. This changing magnetic field causes a voltage across the secondary coil. The size of the voltage depends on the number of turns in the coils. If the secondary coil has more turns than the primary coil, it will have a bigger voltage.

Question 20

What are transformers used for ?

Answer 20

• Transformers are used to ‘step up’ and ‘step down’ voltage in electricity distribution systems to reduce energy losses in transmission lines.
• Transformers are also used in adapter plugs for electronic equipment, e.g. phone chargers, laptops.

Question 21

Non-renewable sources – will eventually run out

Answer 21

Fossil fuels (coal, oil and gas)
Nuclear power.

Question 22

Renewable sources – will not run out

Answer 22

Hydroelectric power
Wind power
Solar power
Geothermal power
Wave power
Tidal power

Question 23

What do generators do ?

Answer 23

Most methods of producing electrical energy use a generator. This transfers kinetic energy (movement) into electrical energy using electromagnetism.

Question 24

To generate electrical energy, a coil of wire must be near a changing magnetic field. This can be done by;

Answer 24

1. Moving a coil near a magnet or

2. Moving a magnet near a coil

Question 25

What does a power rating of an appliance tell us ?

Answer 25

The power rating of an appliance tells us how much electrical energy it changes into other forms every second.

Question 26

Cost of using electrical appliances

Answer 26

The cost of using an electrical appliance is affected by two factors:
• The power rating of the appliance.
• The period of time that it is switched on for.

Question 27

Efficiency of electrical appliances

Answer 27

No appliance is ever 100% efficient, because some electrical energy is always transferred into unwanted forms of energy

Question 28

What does a flex do ?

Answer 28

• The fuse protects the flex from overheating. It melts and breaks the circuit if the current gets too high.