p2. electricity

Question 1

role of switch

Answer 1

turn circuit on ( closed ) and off ( open )

Question 2

role of lamp

Answer 2

electrical current heats up filament bulb to give out light

Question 3

role of resistor compared to fixed resistor

Answer 3

resistor - restricts or limits flow of electrical current
fixed resistor - has resistance that doesn’t change

Question 4

role of variable resistor

Answer 4

• moving slide on this resistor changes resistance
• used to dimmer switches and volume control

Question 5

role of thermistor

Answer 5

• low temperature = high resistance
• high temperature = low resistance
• used in thermostats or heat activated fire alarms

Question 6

role of LDR ( light-dependant resistor )

Answer 6

• low light = high resistance
• high light = low resistance
• used in camera sensors or automatic lights when it gets dark

Question 7

role of diode compared to semi-conductor diode

Answer 7

diode - convert alternating current to direct current
semi-conductor - allows current to flow in one direction only

Question 8

what happens to current,resistance and potential difference throughout a component

Answer 8

greater resistance of component = smaller current for given potential difference across component

Question 9

RP : circuit diagrams to set up and check appropriate circuits to investigate the factors affecting the resistance of electrical circuits

Answer 9

1. connect crocodile clips to resistance wire - 100cm apart
2. record ammeter and voltmeter - resistance
3. move crocodile clips 10cm closer
4. record new ammeter and voltmeter - resistance
5. repeat steps until 10cm apart
6. calculate resistance of each length of wire
7. plot graph

Question 10

what is a series circuit?

Answer 10

all electrical components connected after another in one singular loop

Question 11

properties connected in a series circuit

Answer 11

• same current through each component
• total potential difference of power supply is shared between components
• total resistance of two components is the sum of resistance of each component
  eg. R1 + R2 = R3

Question 12

what is a parallel circuit?

Answer 12

electrical components connected alongside one another,forming extra loops ( branches )

Question 13

components connected in a parallel circuit

Answer 13

• potential difference across each component are the same
• total current through whole circuit is the sum of the currents through separate components
• total resistance of two resistors is less than the resistance of smallest individual resistor.

Question 14

what happens when you add resistors to a series circuit?

Answer 14

• increases total resistance
• as current is the same in every single component within the circuit
• more resistors = harder for current to flow

Question 15

what happens when you add resistors to a parallel circuit?

Answer 15

• decreases total resistance
• more components ( resistors ) added to circuit,so there are more paths for current to pass through

Question 16

RP : use circuit diagrams to construct appropriate circuits to investigate the I–V characteristics of a variety of circuit elements

Answer 16

1. set power supply to 0
2. record ammeter and voltmeter
3. use variable resistor to alter potential difference
4. record new ammeter and voltmeter
5. repeat steps with increasing potential difference slightly each time
6. reverse power supply and repeat steps from 1-5
7. plot graph
8. changed fixed resistor to bub - repeat experiment