P2- current + components

Question 1

what is electric current?

Answer 1

flow of electrical charge.

Question 2

what makes a circuit flow

Answer 2

closed circuit (completed) and source of potential difference

Question 3

what is resistance?

Answer 3

anything that slows the flow down

Question 4

what factors effect resistance?

Answer 4

series, parallel circuit
length of wire

Question 5

what does the GRAPH of a OHMIC CONDUCTOR it look like?

Answer 5

LINEAR (straight line)
because it is a constant tempature

Question 6

what does the GRAPH of a FILAMENT LAMP it look like?

Answer 6

NON-LINEAR
curve at start and end
because as current increases so does the temperature (not constant)

Question 7

what does the GRAPH of a DIODE it look like?

Answer 7

NON-LINEAR
only flow one direction,
flat lines before it has rapid increase

Question 8

what is an LDR

Answer 8

BIRD
brightness increase, resistance decrease

Question 9

what is a thermistor

Answer 9

temperature dependant resistor,
-when hot resistance drops
-cool conditions = high reistance

Question 10

what is a sensing circuit?

Answer 10

turn on or increase power to components depending on conditions,
this is when thermistors or LDRs may be used

Question 11

describe series circuit

Answer 11

-one pathway
-current is same everywhere
-voltage split/shared between components
-increased resistors means overall resistance decreases

Question 12

describe parallel circuit

Answer 12

-multiple pathways
-current split branches
-voltage same everywhere
-increased resistor = overall resistance decreases

Question 13

what does the LIVE wire do? and what does it look like?

Answer 13

-brown
-provides alternating pd at 230v from main supply

Question 14

what does the NEUTRAL wire do? and what does it look like?

Answer 14

-blue
-completes circuit

Question 15

what does the EARTH wire do? and what does it look like?

Answer 15

-green + yellow
-safety feature: stop from becoming live by creating a path for current to flow to ground (prevents electric shock)

Question 16

what is the role of the fuse?

Answer 16

contains thin wire which HEATS up + MELTS if too MUCH CURRENT passes through it. if this happens we say “the fuse has blown”

Question 17

what is the national grid?

Answer 17

-range of different power stations
-interconnected by high voltage transmission lines
-power supply can balance demand over the whole country

Question 18

What is the power station? and it’s voltage supply?

Answer 18

-generate electricity that is transported around country
-25KV

Question 19

What is a pylon? and it’s voltage supply?

Answer 19

supports electricity cables
132KV

Question 20

What is the voltage supply of the consumer?

Answer 20

230kv

Question 21

what is a transformer

Answer 21

increases and decreases voltage at different stages at the national grid

Question 22

Why is the current low when transporting across national grid?

Answer 22

high current means cables get hot and alot of energy wasted on thermal energy making it inefficient. a low current means the voltage must be high. A step-up transformer decreases current and increases voltage. This makes the national grid effiecent as it reduces amount of energy wasted.

Question 23

what is OHMS law ?

Answer 23

-current flowing through a resistor is directly proportional to voltage
-current across a resistor is inversely proportional to resistance

Question 24

what is a direct current?

Answer 24

constantly flowing same direction

Question 25

what is alternation current?

Answer 25

changes direction multiple times per sec, depending on frequency supply