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Ashley Reyes Physics > Electricity > Flashcards

Electricity Flashcards

1
Q

Electric current is a flow of __________ ______.

A

Electrical Charge

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2
Q

The size of the current is the ____ __ ____ __ ______.

A

Rate of flow of charge

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3
Q

Equation for charge flow :

A

Charge flow = current × time

Q = I × t

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4
Q

Equation for potential difference:

A

Potential difference = Current × Resistance

V = I × R

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5
Q

R is constant in…

A

V = I × R

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6
Q

An LDR is a ________ that is _________ on the _________ of _____.

A

An LDR is a resistor that is dependant on the intensity of light.
In bright light the resistance falls.
In darkness the resistance is highest.

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7
Q

A thermistor is a ___________ _________ resistor.

A

A thermistor is a temperature dependant resistor.
In hot conditions, the resistance drops.
In cool conditions, the resistance goes up.

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8
Q

Series circuits:

A

In series circuits the total potential difference of the supply ie shared between various components.
The P.D. of a series circuit always adds up to equal the source P.D.
The same current flows through ALL components.
The total of resistant of 2 components is just the sum of their resistances.

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9
Q

Parallel Circuits:

A
  • In parallel circuits ALL components get the full source P.D , so the potential difference is the same across all components.
  • The total current flowing around is I’d equal to the total from the source current.
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10
Q

What are the 2 types of electricity supplies ?

A

ac: - Alternating current
dc: - Direct current

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11
Q

Alternating currents:

A

The current is constantly CHANGING direction. They are produced by alternating VOLTAGES, where positive and negative ends keeo alternating.

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12
Q

Direct current:

A

Is a current that is always flowing in the SAME direction. It is created by a direct VOLTAGE.

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13
Q

Neutral wire:

A

Blue
Completes the circuit and carries away current.
Electricity normally flows IN through the LIVE wire and OUT through the NEUTRAL WIRE.
It is around 0 V

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14
Q

Live wire:

A

Brown.
The live wire provides the ALTERNATING P.D from the mains supply.
It is at about 230 V

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15
Q

Earth wire:

A

Green and Yellow.
Protecting the wiring from safety. Stops the appliance from becoming LIVE.
Doesn’t usually carry a current only when there is a FAULT .
0 V.

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16
Q

How is an electric shock produced ?

A

A large potential difference is produced across your body and a current flows through you.

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17
Q

Kettle transfer energy…

A

Electrically from the mains ac supply to the thermal energy store of the heating element inside the kettle

18
Q

Energy is transferred…

A

Electrically from the battery of a handheld fan to the kinetic energy store of the fans motor

19
Q

Equation for energy transferred

A

Energy Tranferred = power × time
E = p × t

Energy transferred = Charge flow × PD
E = Q × V

20
Q

The power of an appliance is…

A

The energy that it transfers per second.

21
Q

The power rating tells you…

A

The maximum amount of energy transferred between stores per second when the appliance is used.

22
Q

When an electrical charge goes through a change in potential difference…

A

The energy is transferred

23
Q

Energy transferred:

A

Energy transferred = Charge flow × P.D.

E = Q × V

24
Q

Equations for power:

A 
Power = Energy ÷ Time
P = e ÷ t
Power = P.D. × Current 
P = V ×I
Power = Current (squared) × Resistance
P = I^2  × R
25
Q

Step up transformer :

A

Increases the P.D. and reduces the current.

So it it causes less heatbti be produced so it is more efficient. Less energy is wasted.

26
Q

Step down transformer:

A

Decreses P.D. and increases current.

This is so it is safe to use in homes

27
Q

Static electricity:

A

When certain undulating materials are rubbed together, negatively charged electrons will be scraped off and dumped on one another.
This leaves the materials electrically charged with a positive static charge on one and an equal negative static charge on the other.

28
Q

Both positive and negative electrostatic charges are only produced by…

A

The movement if electrons

29
Q

An electric field is created…

A

Around any electrically charged object

30
Q

The closer you get to the object…

A

The stronger the field is

31
Q

Electric field lines go from

A

Positive to negative

32
Q

The closer the lines are

A

The stronger the field is. You can see that the further from a charge you are the further apart the lines are ( a weaker field)

33
Q

Unit for potential difference

A

Volts

V

34
Q

Symbol for potential difference

A

V

35
Q

Unit for resistance

A

Ohms

♎

36
Q

Symbol for resistance

A

R

37
Q

Unit for Current

A

Amps

A

38
Q

Symbol for Current

A

I

39
Q

Unit for charge

A

Coulombs

c

40
Q

Symbol for charge

A

Q

41
Q

Unit for time

A

Seconds

s

42
Q

Symbol for time

A

t

Ashley Reyes Physics (1 decks)

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