Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > Electricity and Circuits > Flashcards

Electricity and Circuits Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What three subatomic components make up an atom?

A

Protons
Neutrons
Electrons

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

Describe the structure of an atom

A

Protons and neutrons in the nucleus
Electrons surrounding the nucleus in shells

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

How is current defined

A

The rate of flow of electrons around a circuit

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

What two ways that a component can be connected in a circuit?

A

Series (same loop)
Parallel (adjacent loop)

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

Describe series circuits

A

Closed circuit
Current is the same everywhere
The p.d is shared between each component.

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

Describe parallel circuits

A

Branched circuit
Current splits into multiple paths
The p.d across each component is the same on each branch.

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

Where must the voltmeter be placed in a circuit?

A

In parallel with the component that is being measured.

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

What two factors does the current in a circuit depend on?

A

Potential difference
Resistance

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

What happens when current reaches a junction in a circuit?

A

Current is conserved; the total current remains the same and is split between the two branches.

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

How does resistance affect the current in a circuit?

A

As the total resistance of a circuit increases, the current flowing through the circuit decreases.

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

How can the current in a circuit be varied?

A

Using a variable resistor

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

How is total resistance affected by two resistors in a series circuit?

A

The total resistance increases; it is equal to the sum of two resistors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is total resistance affected by two resistors in a parallel circuit?

A

The total resistance decreases

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

What is an ohmic conductor?

A
  1. A conductor for which current and potential difference are directly proportional.
  2. Resistant remains constant whilst current changes.
  3. Temperature must be constant.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

List four components in which resistance is not constant when current changes

A
  1. Filament lamps
  2. Diodes
  3. Thermistors
  4. Light dependent resistors (LDRs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to the resistance of a filament lamp as the temperature increases? Why? (3)

A
  1. Resistance increases
  2. Metal ions have more kinetic energy, so vibrate more, colliding more frequently with electrons as they flow through the metal.
  3. This creates more resistant to current flow.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is different about current flow through a diode?

A

The current only flows in one direction.
Resistance is very high in other direction, preventing current flow.

18
Q

State what happens to the resistance of a thermistor as temperature increases

A

The thermistor resistance decreases

19
Q

Give two examples of when a thermistor may be used

A
  1. In a thermostat, to turn a heater on below a certain temperature.
  2. In a freezer, to turn on a cooler when temperature is too high.
20
Q

State what happens to the resistance of an LDR as light intensity decreases

A

The resistance increases

21
Q

Give an application for LDR

A

Street lamps - when light levels drop at night, resistance increases and the light gains sufficient current to turn on.

22
Q

How do diodes work?

A

A diode only allows current to flow in one direction.
If current is flowing the right way, the resistance is large for small voltages, but then at higher voltages becomes very small.

23
Q

What factors affect the energy transferred when charge flows through a component?

A

Amount of charge
The potential difference across the component

24
Q

Define potential difference

A

The work done per unit charge

25
Q

When an electrical current flows through a resistor why does it heat up?

A

There are collisions between the electrons and the ions in the resistors lattice.
This causes a transfer in kinetic energy into thermal energy, which is released into the surroundings.

26
Q

How do low resistance wires reduce unwanted energy transfers?

A

A smaller resistance means fewer collisions, therefore less energy will be wasted through heating.

27
Q

Define power

A

The energy transferred per second/The rate of energy transfer

28
Q

Give equations linking power and resistance

A

power = (current)^2 x resistance
power = (potential difference)^2 / resistance

29
Q

What does AC mean?

A

Alternating current
This is current which is constantly changing between a negative and a positive maximum.

30
Q

What does DC mean?

A

Direct current
This is current which takes a constant value.

31
Q

Is mains electricity an AC or DC supply?

A

Mains electricity is an AC supply.

32
Q

What is meant by the frequency of a supply?

A

This is the rate at which AC current changes.

33
Q

What is the frequency and voltage of the UK mains electricity supply?

A

Frequency: 50Hz
Voltage: 230V

34
Q

What type of current do batteries and cells supply?

A

Direct current

35
Q

What is the power rating of an appliance?

A

It shows how much energy a device converts per second.

36
Q

What wires does a typical appliance have?

A

Live wire - brown
Neutral wire - blue
Earth wire - green and yellow

37
Q

Explain when earth wires does and doesn’t carry a current

A

Under normal circumstances, no current flows through the earth wire.
Current flows when a fault occurs in the appliance.

38
Q

What is the purpose for neutral wires?

A

To complete the circuit by connecting the appliance back to the mains supply.

39
Q

How does a fuse stop a device from getting damaged?

A

When the current becomes too high the fuse wire will melt and break, therefore stopping current from flowing to the appliance and preventing damage.

40
Q

Why is it important to connect a fuse or switch to the live wire?

A

When the switch is turned off, or when the fuse breaks, it will break the circuit and stop current flowing through the wire. This provides a method to stop current flowing through appliances.

41
Q

Why is it dangerous to have a connection between earth and live wires?

A

It can result in a surge, causing electric shocks

Physics (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions