electronics

Question 1

what does a system contain

Answer 1

an input process and output

Question 2

example of how a bicycle works using input process and output

Answer 2

input - turning of the cyclists legs
process - chain and sprockets
output - rear wheel which propels e bike forward

Question 3

what are circuits made of

Answer 3

components which are joined together by wires

Question 4

what are PCB’s

Answer 4

• printed circuit boards
• boards with thin copper tracks (instead of wires) connecting components in a circuit

Question 5

why are PCBS used

Answer 5

to reduce the size and the manufacturing cost of electronic systems

Question 6

what is a conductor

Answer 6

a material that allows electricity to flow through it

Question 7

why is copper used for wire tracks

Answer 7

because it is ductile, malleable and a good conductor

Question 8

what does voltage do

Answer 8

pushes current around a circuit

Question 9

what do resistors do

Answer 9

they reduce the current in a circuit so that you don’t damage delicate components

Question 10

what do input devices do

Answer 10

they receive an external signal which triggers a system to worn

Question 11

what do switches do

Answer 11

they turn a circuit on and off
- closed switch allows current to flow through a circuit

Question 12

examples of switches

Answer 12

• toggle switch- flick to one position to complete the circuit
• push switch - push down and hold to complete or break the circuit
• slide switch - slide to one side to complete the circuit

Question 13

what do variable resistors do

Answer 13

they change the resistance of a circuit based on an external factor

Question 14

what are thermistors

Answer 14

• resistors that detect changes in temperature
• in hot conditions, t
  resistance falls, in cold, it increases
• used in central heating systems which turn off when a room reaches a certain temperature

Question 15

what are LDRs and their uses

Answer 15

• light sensors, detect changes in light levels
• in brighter light, resistance falls
• used in automatic night lights

Question 16

what are pressure sensors and their used

Answer 16

• detect changes in pressure in a system
• depending on the type of pressure sensor, resistance can either increase or decrease as pressure increases
• often used in equipment where gases or liquids are monitored. in cars, they are used to detect if there’s a leak in the fuel system. a leak would cause pressure to fall and this would trigger a warning light to come on

Question 17

what do process devices do

Answer 17

receive inputs and determine the output

Question 18

what are IC’s and what do they do and their advantages

Answer 18

• Integrated circuits are tiny, self contained circuits with billions of components built in
• they help simplify electronic systems by reducing the number of separate components needed in a circuit
• meaning they are cheaper and smaller, also use much less power because of their size

Question 19

what is a microcontroller

Answer 19

• a mini computer on a chip which has a processor, memory and one or more inputs and outputs

Question 20

advantages of microcontrollers

Answer 20

• can do the job of multiple IC’s
• unlike other IC’s, most can be reprogrammed for a different use

Question 21

disadvantages of microcontrollers

Answer 21

more expensive than IC’s

Question 22

where is the program stored in a microcontroller

Answer 22

in the microcontrollers onboard memory

Question 23

examples of microcontroller boards

Answer 23

Arduino boards and BBC micro:bit

Question 24

ways to programme a microcontroller

Answer 24

• writing a series of commands using a programming language such as BASIC and scratch
• creating a flowchart telling the microcontroller exactly when to start, how to make decisions based on input signals, when to add a time delay to the process, what to output and when to stop operating

Question 25

how is programming done

Answer 25

using specialist computer software such as PICAXE and Logicator

Question 26

what are timers used for

Answer 26

to add a time delay to a process and make sure parts of a program are running when they’re supposed to
- they can generate a pulse after a particular length of time has passed

Question 27

how do counters differ from timers

Answer 27

they count pulses of voltage produced by an input device

Question 28

how are microcontrollers used as timers

Answer 28

• microcontrollers controlling flashing lights like car indicators, use timers to set the time that the light is on and off for
• microcontrollers in microwaves use a timer to set the length of time that the oven cooks for

Question 29

how are microcontrollers used as counters

Answer 29

• most modern cars have a dial on the dashboard that shows how fast the engine is turning ( the number of revolutions per minute)
• a microcontroller is used to count the number of revolutions

Question 30

what do logic gates do

Answer 30

• they make decisions in ICs based on a collection of inputs

Question 31

what are the types of logic gates

Answer 31

OR gates
AND gates
NOT gates

Question 32

describe how OR gates work

Answer 32

• OR gates have 2 inputs. if one input or the other is on, then the output is on
• For example, an automatic door will open if a sensor detects someone on the outside or inside

Question 33

how do AND gates work

Answer 33

• They have two inputs: both inputs need to be on for the output to be on.
• for example a tumble dryer is won’t start until both the start button is pressed and an input sensor has detected that the door is closed

Question 34

how does an NOT gate work

Answer 34

They have one input: if the input is on the output is not on. It reverses the input

Pressing an emergency stop switch will stop the output on an escalator but it would cause it to stop moving

Question 35

examples of output devices

Answer 35

LEDs, lamps and bulbs - turn electricity into light

Buzzers - make a noise

Speakers - turn electrical signals into sound