P4 - circuit electricity

Question 1

Describe a single cell

Answer 1

Provides the circuit with a source of potential difference

Question 2

Describe a battery of cells

Answer 2

A battery is two or more cells

Question 3

Describe a switch

Answer 3

Turn the circuit on (closed),or off (open)

Question 4

Describe a resistor

Answer 4

A resistor limits the flow of current

Question 5

Describe a fixed resistor

Answer 5

A fixed resistor has a resistance it cannot change

Question 6

Describe a thermistor

Answer 6

The resistance of a thermistor depends on the temperature ,as it’s temperature increases then the resistance increases.

Question 7

What does LDR stand for

Answer 7

Light dependent resistor

Question 8

Describe a LdR

Answer 8

The resistance of LDR depends on the light intensity

Question 9

What is a electric current

Answer 9

It’s the flow of charge

Question 10

What charge do electrons carry

Answer 10

A negative charge

Question 11

What determines the size of the current

Answer 11

Determined by the flow of charge (the flow of charge per second)

Question 12

Why are metals good conductors?

Answer 12

Metals contain lots of free electrons that can move freely between the positively charged metal ions

Question 13

What is the equation to calculate charge?

Answer 13

q= It

Question 14

What is the unit for charge?

Answer 14

Coulombs , C

Question 15

What is the unit for current?

Answer 15

Amps,A

Question 16

What is the equation for potential difference?

Answer 16

V= E/q or E= Vq

Question 17

What’s it called when electrons that pass through a wire have to push their way through lots of vibrating ions in the metal?

Answer 17

Resistance

Question 18

What’s the equation for resistance?

Answer 18

Resistance= potential difference/ current
V=IR

Question 19

What is resistance measured in?

Answer 19

Ohms

Question 20

The longer the wire the ………… resistance

Answer 20

Higher

Question 21

What are the series circuit rules?

Answer 21

Current - stays the same
Voltage - shared between the components
Resistance- add together
R total = R+ R2+R3…

Question 22

What are the parallel circuit rules?

Answer 22

Current- split along branch
Voltage - stays the same
Resistance- as more resistors are added,total resistance increases.

Question 23

Describe a fixed resistor graph

Answer 23

• constant gradient
  -directly proportional
  -straight line
  -through origin 0,0