Topic 5- Electricity and Circuits Flashcards Preview

Physics > Topic 5- Electricity and Circuits > Flashcards

Flashcards in Topic 5- Electricity and Circuits Deck (42):
1

Current is...
Unit?

the flow of electrical charge around the circuit
Unit- amps

2

Potential difference/ voltage is...
Unit?

the driving force that pushes the charge around
Unit- volts

3

Resistance is...
Unit?

anything that slows the flow of the circuit down
Unit- ohm

4

The current flowing through a component depends on ... and ...

the potential difference across it and the resistance of the component

5

Usually the higher the potential difference the...

higher the current will be

6

The greater the resistance the...

smaller the current that flows

7

In metals the current is caused by...

A flow of electrons

8

Charge?
(3 things)

Current is the rate of flow of charge
Depends on current and time
Unit- coulombs

9

Potential difference is the energy transferred ...

Per coulomb of charge that passes between two points in an electrical circuit

10

Electrical charge flow has to do work against resistance, this causes ...

an electrical transfer of energy
(work done = energy transferred)

11

Some of the energy from the flow working against the resistance is used usefully, however some is...
Because...

Dissipated to the thermal energy stores of the component and the surroundings
Because the electrons collide with the ions, the ions gain more energy, causing them to vibrate and therefore heat up

12

As the resistor heats up (given the p.d)...

the current decreases

13

If the resistor gets too hot...

No current will be able to flow

14

Ammeter measures...
Must be placed...

The current flowing through the component
Must be placed in series (never parallel) with the component but can go anywhere in the circuit

15

Voltmeter measures...
Must be placed...

The potential difference across the component
Must be placed in parallel

16

After finding the range of currents with a diode, swap the diodes direction and you should find that...

current cannot flow through the diode anymore

17

If you keep the supply of potential difference constant, gradually heat the thermistor and the current through the thermistor...

Increases as the resistance decreases

18

LDRs show that if you keep a constant supply of p.d and slowly increase the light intensity/levels, the current through the LDR...

Increases as resistance decreases

19

Non linear graphs (curved line) ...

a filament lamp
diode

20

Linear graph (straight line) ...

a fixed resistor

21

(shown in a graph) current is directly proportional to...

p.d
(straight line- steepness of line changes depending on the resistor)

22

(shown in a graph) the increasing current increases the...

temperature of the filament, which makes the resistance increase
(curved line)

23

(shown in a graph) current will only flow through a diode in...

one direction
therefore the diode has a very high resistance in one direction of the graph so no current can flow through and opposite in the opposite direction

24

LDR stands for?
What happens in bight light?
No light?
Examples?

Light dependant resistors
In bright the resistance decreases
In no light the resistance increases
Eg. automatic night lights, outdoor lighting and bugler detectors

25

A thermisitor is a...
In hot conditions?
Cold?
Examples?

A temperature dependant resistor
In hot conditions the resistance decreases
In cold conditions the resistance increases
Eg. car engine temperature sensors and electronic thermostats

26

Series circuits, if you remove or disconnect one component...

the circuit is broken and the other components stop working

27

The current in a series circuit is...

the same everywhere

28

Parallel circuits, if you remove or disconnect one of the components...

it will not effect the other components

29

The total p.d in a series circuit is...

shared between components

30

The total resistance in a series circuit...

increases as you add resistors

31

Current in a parallel circuit is...

shared around into the different components

32

The p.d of a parallel circuit is...

the same across all components

33

The total resistance of a parallel circuit...

decreases if you add a second resistor in parallel

34

The larger a current through or p.d across, a component...

the more energy is transferred

35

When an electrical charge goes through a change in potential difference, then .... is transferred.
And then what happens...

Energy.
Then energy is supplied to the charge at the power source to raise it through a potential
The charge gives this energy when it falls through any potential drop in components

36

Kettles transfer energy electrically from the mains a.c supply to...

the thermal energy store of the heating element inside a kettle

37

Handheld fans transfer energy electrically from the battery to...

kinetic energy store of the fan's motor

38

The higher the current, the more energy is...

transferred to the thermal energy stores of the component and then also the surroundings

39

Heating up a component does generally decrease...

the efficiency of the component
less energy is transferred to the useful energy stores

40

Heating of a component can be useful, example?

Toaster- contains a coil of wire with a really high resistance, current passes through which increase the temperature so much the coil glows and gives off infrared radiation. This radiation then transfers energy to the bread and cooks it.

41

The power of an appliance is the energy...

transferred per second

42

The power rating tells you...

the maximum amount of energy transferred between stores per second when the appliance is in use