Everything

Question 1

What is an LDR

Answer 1

Light Dependent Resistor : component where resistance varies with light intensity e.g vehicle headlights

Question 2

What is a thermistor

Answer 2

Component where resistance varies with temperature e.g digital thermometers, fire alarms

Question 3

What do the LDRs and Thermistors have in common

Answer 3

As heat/light increases so does the resistance ( directly proportional )

Question 4

Units for charge flow

Answer 4

Coulombs

Question 5

Units for current

Answer 5

Amperes

Question 6

What do step up transformers do

Answer 6

• increase p.d
• decrease current

Question 7

Why is less current good for step ups?

Answer 7

• Less current means less heat generated
• Less heat lost by dissipation
  More efficient

Question 8

What do step down transformers do

Answer 8

• decrease p.d
• increase current
• power is restored for domestic and commercial use therefore much safer

Question 9

Direct current

Answer 9

Current that flows in one direction only ( from cell/battery )

Question 10

What is a.c

Answer 10

Current that switches directions around a loop ( from the mains )

Question 11

What frequency is the Uk mains

Answer 11

50hz

Question 12

What is the p.d in the sockets

Answer 12

230v

Question 13

What is a d.c generator called and what does it do

Answer 13

Dynamo, produced positive cycles to be shown on an oscilloscope

Question 14

What is an a.c generator called and what does it do

Answer 14

Alternator, used in power stations to generate huge amounts of electricity

Question 15

How does a power station work basic

Answer 15

A rotating drum of magnets induces a current in stationary coils

Question 16

What does live do

Answer 16

• Alternates between positive and negative current
• connected via a fuse within the plug to a device

Question 17

What does neural do?

Answer 17

• Remains at 0v ( practically )
• acts as the completor for the circuit to do a whole loop

Question 18

What does the earth wire do

Answer 18

• Only carries current is the device is faulted and the metal casing has a current flowing from the live
• carries the current from the metal out casing back to the power supply

Question 19

Equations for frequency

Answer 19

Frequency = 1/ time period ( time for one oscillation)

Question 20

Equation for power in a component

Answer 20

Power = current * p.d
( w )

Question 21

What is power

Answer 21

The power of a device is the rate at which it transfers energy. Therefore the amount of energy transferred in an amount of time

Question 22

What is 1w equal to

Answer 22

1 joule per second

Question 23

What is the equation for power in a device?

Answer 23

Power = energy transferred / time taken
( in joules ) ( s )