P5.2

Question 1

Give three examples of components,what do they resist?

Answer 1

Resistors,lamps,motors

They resist the flow of charge through them

Question 2

The resistance of connecting wires is….

Answer 2

So small that it can usually be ignored

Question 3

Two or more resistors in SERIES have more resistance than either one on its own,
Why?

Answer 3

Because the battery has to move charges through both of them

Question 4

Two (or more) resistors in parallel provide…

What does this mean?

Answer 4

More paths for charges to move along that’ll either resistor on its own
• so total resistance is less

Question 5

Power (watts) =

Answer 5

Voltage (volts,v) X current (amperes,A)

Question 6

Resistors get hotter when there is an…

Answer 6

Electric current through them

Question 7

This heating effect is caused by what?

Answer 7

Collisions between the moving charges and stationary ions in the wire

Question 8

What does this heating effect make?

Answer 8

A lamp filament (bulb) hot enough to glow

Question 9

What happens to the current when you increase the voltage?

Answer 9

Increase V, increase current in proportion

Double v,double current

Question 10

The larger the voltage the ______ the current

Answer 10

Bigger

Question 11

The larger the resistance,the _______ the current

Answer 11

Smaller

Question 12

As light intensity increases, current flowing ________

Answer 12

Increases

Question 13

Light intensity increases,resistance ________

Answer 13

Decreases

Question 14

As the resistance of LDR decreases,light intensity _______

Allowing what to happen?

Answer 14

Light intensity increases,allowing more current to flow

Question 15

When bright,the resistance is ______

What does this make LDR’s useful for?

Answer 15

Resistance is high,useful for automatic night lights

Question 16

When temperature increases,resistance ______ allowing what to happen?

Answer 16

Resistance decreases,allowing more current to flow

Question 17

When the temperature is low,the resistance is _______

This makes a thermistor useful for what?

Answer 17

Reistance is higher,useful for electronic thermostats

Question 18

Resistance (ohms) =

Answer 18

Voltage (C) divided by current (amperes)

Question 19

Fixed resistor

What is it used for?

Answer 19

To limit the flow of a current to a particular component

Question 20

LDR

Answer 20

Converts light —-> electrical resistance

Question 21

Power is a measure of….

Answer 21

A measure of the rate at which an electrical power supply transfers energy to an appliance or device and/or its surroundings