Electricity - Paper 1 Flashcards

To revise the key points from the Electricity topic (paper 1)

You may prefer our related Brainscape-certified flashcards:
1
Q

Draw the circuit symbol for a lamp

A

an X in a circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Draw the circuit symbol for a diode

A

An arrow head in a circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Draw the circuit symbol for a resistor

A

A rectangular box

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Draw the circuit symbol for a variable resistor

A

A rectangular box with a diagonal arrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Draw the circuit symbol for an LED

A

Same as a diode with 2 arrows points away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Draw the circuit symbol for a fuse

A

A rectangular box with a horizontal one running through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Draw the circuit symbol for a voltmeter

A

V in a circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Draw the circuit symbol for an ammeter

A

A in a circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Draw the circuit symbol for a thermistor

A

a rectangular box with a diagonal line through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Draw the circuit symbol for an LDR

A

A rectangular box in a circular with 2 arrows pointing towards it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define Current

A

Flow of charge (electrons) measured in amps (A)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

State the equation that links charge, current and time.

A
Charge = Current x time 
Q = It
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the units of charge

A

Coulombs (C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the relationship between current and resistance?

A

As resistance increases, current decreases and vice versa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State the equation that links potential difference, current and resistance

A

Potential difference = Current x resistance

V = IR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State the units of potential difference

A

Volts (V)

17
Q

State the units of resistance

A

Ohms

18
Q

State the relationship between the length of wire and its resistance.

A

As the length of the wire increases the resistance increases. they are directly proportional

19
Q

As more resistors are added in series what happens to the total resistance.

A

Total resistance increases (Rt = R1 + R2 + …..)

20
Q

State ohms law

A

Current is directly proportional to potential difference constant temperature. this means resistance remains constant.

21
Q

Sketch the I/V graph for a resistor

A

A straight line through the origin (current and potential difference are directly proportional - an ohmic conductor)

22
Q

Sketch the I/V graph for a bulb

A

It starts off as a straight line through the origin but the the current levels offs so the graph curves. Non ohmic conductor

23
Q

How does the resistance of a lamp change as it heats up?

A

As temperature increases resistance increase. Atoms/ions have more energy so vibrate more taking up more space making it harder for electrons to travel down the wire.

24
Q

Sketch the I/V graph for a diode

A

Current can only flow in one directions. So zero current in the negative direction but in the positive direction current increases slightly after the origin. Non ohmic conductor

25
Q

State the relationship between temperature and resistance for a thermistor

A

As temperature increases resistance decreases.

26
Q

State some uses of thermistors

A

In thermostats to turn circuits on/off if they get too hot to cold e.g. in an iron, hair straighteners etc

27
Q

State the relationship between temperature and light intensity for a LDR

A

As light increases increases, resistance decreases

28
Q

State some uses of LDRs

A

In circuits to switch lights on when it gets dark

29
Q

state the rules for current, potential difference and resistance in a series circuit

A

Current - same flowing through each component
Potential difference - the p.d. of the power supply is shared between the other components
Resistance - the total resistance increases as more components are added. the total resistance is the sum of all the individual components resistance

30
Q

state the rules for current, potential difference and resistance in a parallel circuit

A

current - splits up but the total current stays the same
Potential difference - across each brach is the same as from the battery
Resistance - decreases as more branches are added. the electrons have more choice of paths to take.

31
Q

What happens when electrical current flows through a resistor?

A

Electrical energy is transformed into heat energy

32
Q

What is a short circuit?

A

An electrical circuit that allows current to travel along unintended paths with no or very low resistance Resistance low = current very high. This will cause the battery to overheat

33
Q

Why do lamps blow when they have just been turned on?

A

The lamp is cold so low resistance, high current flows - sometimes enough to melt the wire in the bulb

34
Q

In a potential divider, what happens to voltage when two resistors are equal?

A

They share applied voltage equally

35
Q

In a potential divider, a current passes through a resistor then through a thermistor. How does the voltage across each component change as temperature decreases?

A

The thermistor cools. The resistance of the thermistor rises, taking a larger share of input voltage. As the input from the battery is constant so output voltage rises across the fixed resistor.

36
Q

In a potential divider, a current passes through a resistor then through a thermistor. How does the voltage across each component change as temperature increases?

A

The thermistor heats up. The resistance of the thermistor decreases, taking a smaller share of input voltage. As the input from the battery is constant so output voltage decreases across the fixed resistor.

37
Q

In a potential divider, a current passes through a resistor then through an LDR. How does the voltage across each component change as light intensity increases?

A

If light intensity increases the resistance of the LDR decreases. The LDR will take a smaller share of the input voltage. As the input voltage from the battery is fixed the output voltage across the fixed resistor must increase.

38
Q

In a potential divider, a current passes through a resistor then through an LDR. How does the voltage across each component change as light intensity decreases?

A

If light intensity decreases the resistance of the LDR increases. The LDR will take a larger share of the input voltage. As the input voltage from the battery is fixed the output voltage across the fixed resistor must decrease.