Brainscape's Knowledge GenomeTM

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


See full index

Physics- P2 > P2.3 Currents in electrical circuits > Flashcards

P2.3 Currents in electrical circuits Flashcards

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

What happens when 2 electrically charged objects are brought together?

A

they exert a force on each other

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

When will 2 objects attract?

A

if the 2 objects carry different types of charge (have opposite electric charge +, -)

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

When will 2 objects repel?

A

When the 2 objects carry the same type of charge ( +,+ or -, -)

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

What materials can electrical charges move easily through?

A

good conductors- eg metals

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

What is electric current?

A

a flow of electric charge

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

What is the size of electric current?

A

the rate of flow of electric charge

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

in the equation

I = Q (divided by) t

what do the letters stand for and what are the units?

A

I- current in amps (A)

Q- charge in coulombs (C)

t-time (s)

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

When does more charge pass around a circuit?

A

when a bigger current flows

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

What is potential difference (voltage) ?

A

the energy transferred per coulomb of charge that passes between 2 points in a circuit

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

What is resistance?

A

Anything in the circuit which slows the current down

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

The greater the resistance across a component…….

A

the smaller the current that flows

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

What is the potential difference between 2 points in an electrical circuit?

A

the work done (energy transferred) per coulomb of charge that passes between the points

(amount of energy that is transferred per unit of charge)

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

In the equation

V = W (divided by) Q

what does each letter stand for and what are the units?

A

V- potential difference (V)

W- work done (J)

Q- charge in coulombs (C)

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

What is another word for voltage?

A

potential difference (p.d)

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

Describe a thermistor and its uses

A
  • is a temperature dependent resistor
  • in hot conditions the resistance drops, so more current
  • in cool conditions the resistance goes up, so less current
  • make useful temperature detectors eg- thermostats + car engine temperature sensors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe light dependent resistors (LDR) and its uses

A
  • dependent on INTENSITY of light
  • bright light, resistance falls- more current
  • darkness, resistance increases- less current
  • useful as automatic night lights, out door lighting and burglar detectors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are current-potential difference graphs used to show?

A

how the current through a component varies with the potential difference across it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens when certain insulating materials are rubbed against each other?

A

They become electrically charged

because negatively charged electrons are rubbed off one material and on to the other

The material that gains electrons becomes negatively charged and the material that loses electrons is left with an equal positive charge

The electrically charged materials attract smaller objects near them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the current-potential difference graph for a resistor
(eg LDR or thermistor)

A

The current through a resistor is directly proportional to the P.D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the current-potential difference graph for a resistor
(eg LDR or thermistor)

A

The current through a resistor is directly proportional to the P.D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why in an LDR the more light, the more current?

A

as with more light there is less resistance

this is because light allows electrons to have energy and flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why in a thermistor the higher the temperature, the greater the current?

A

as the higher the temperature, the less resistance

This is because the temperature causes the electrons to have more energy and move due to increased kinetic energy of particles

23
Q

Describe the current-potential difference graph for a filament lamp

A

a curve

as the temperature of the filament increases and resistance increases

24
Q

In a filament bulb, why does increasing the temperature increase the resistance?

A

with a higher temperature, the ions in the conductor vibrate more which makes it harder for the electrons to get through the resistor, meaning the resistance increases

25
Q

How can the resistance of a component be found?

A

by measuring the current through, and potential difference across the component

26
Q

In the equation

V= I x R

what do each of the letters stand for and what are the units?

A

V- potential difference (V)

I- current (A)

R- resistance in ohms

27
Q

On a current-potential difference graph, the steeper the gradient….

A

the lower the resistance

28
Q

On a current-potential difference graph, what does it mean if the graph curves?

A

the resistance is changing

29
Q

The current through a component depends on its ….

A

resistance

30
Q

The greater the resistance in a component, the ……….. the current through the component

A

smaller

31
Q

What are the rules for components connected in series?

A

total resistance is the sum of resistance of each component

same current through each component

total P.D of the supply is shared between the components

32
Q

What are the rules for components connected to parallel?

A

The P.D across each component is the same

Total current through circuit is the sum of the currents through separate components.

33
Q

What happens if you remove or disconnect one of the components from a series circuit?

A

The circuit is broken and all the components stop working

34
Q

There is a bigger potential difference in a series circuit when…

A

more cells are in the circuit

35
Q

In a parallel circuit, why do identical bulbs have the same brightness?

A

Because in parallel circuits, the potential difference is the same across all components

36
Q

In a series circuit, why do identical bulbs not have the same brightness?

A

As in series circuits, potential difference is shared across all components

37
Q

Ammeters are always connected in….

A

series

even in parallel circuits

38
Q

Voltmeters are always connected in…

A

parallel with a component

even in a series circuit

39
Q

Why is it important that ammeters have very low resistance?

A

So the ammeter affects the current as little as possible

40
Q

What does an ammeter do?

A

Measures the current in amps flowing through the components

41
Q

In a circuit, where can an ammeter be placed?

A

anywhere in series in the main circuit but never in parallel like the voltmeter

42
Q

What does a voltmeter do?

A

it measures the potential difference in volts across a component

43
Q

Where is a voltmeter placed in a circuit?

A

must be placed in parallel around the component under test

NOT around the variable resistor or battery

44
Q

Describe the current through a diode

A

current through a diode flows in 1 direction only. The diode has a very high resistance in the reverse direction

45
Q

Why is there an increasing use of LED lighting?

A

as they use a much smaller current than other forms of lighting

46
Q

When does an LED emit light?

A

When a current flows through it in the forward direction

47
Q

What do LEDs stand for?

A

light emitting diodes

48
Q

What causes a driver in a car to become charged?

A

the drivers clothing and the car seat rub together

the friction causes electrons to transfer from either the seat to the driver or from the driver to the seat

49
Q

Why does the resistance of the metal filament inside the bulb increase as the potential difference across the bulb increases?

A

exam answer-

metals contain free electrons

as temperature of the filament increases, ions vibrate faster

electrons collide more frequently with the ions

so velocity of electrons decreases

50
Q

Why does a diode cause the trace on a oscilloscope screen to change?

A

diode has a large resistance in the reverse direction

so it stops the current to flow in that direction

51
Q

Why does electric charge flow more easily through copper

A

because copper has a low resistance

52
Q

In simple terms, why does the resistance of a bulb increase as the potential difference across the bulb increase

A

as the temperature of the bulb increases

53
Q

When obtaining data to plot a current-potential difference graph, why is a variable resistor used?

A

to obtain a range of p.d values

Physics- P2 (6 decks)

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