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Physics > P2 Electricity > Flashcards

P2 Electricity Flashcards

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1
Q

What Is the equation for potential difference?

A

Potential difference = current x resistance V = IR

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2
Q

What is current?

A

Flow of charge per second

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3
Q

What moves around a circuit

A

Electrons

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4
Q

What is charge measured in?

A

Coulombs (C)

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5
Q

What is potential difference measured in?

A

Volts (V)

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6
Q

What is resistance measured in?

A

Ohms

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7
Q

What is current measured in?

A

Amperes/ Amps (A)

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8
Q

Which direction does current move in?

A

The opposite direction to the electrons

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9
Q

What is the equation for charge?

A

Q = It
Charge = current x time

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10
Q

What is the rule for current in a series circuit?

A

Current is the same at all points

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11
Q

What is the rule for potential difference in a series circuit?

A

V1 = V2 + V3

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12
Q

What is the rule for potential difference in a parallel circuit?

A

Pd is the same across all branches

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13
Q

What is the rule for current in a parallel circuit?

A

I1 = I2 +I3

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14
Q

What is electrical resistance?

A

A measure of a components opposition to the flow of current.

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15
Q

What happens if the resistance of a variable resistor is increased?

A

The current will decrease

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16
Q

What is an ammeter?

A

Used to measure current, placed in series

17
Q

What is a voltmeter?

A

Measures potential difference, placed in parallel

18
Q

How do we collect negative values of current and resistance?

A

Swap the connecting leads at the terminal of the battery

19
Q

What does ohmic mean?

A

Directly proportional relationship between current and potential difference

20
Q

What does the graph of a constant resistor look like?

A

Diagonal straight line through the origin (positive)

21
Q

What does the graph of a filament lamp look like?

A

F

22
Q

If the line is steep, what is the resistance?

A

Low

23
Q

How does a filament lamp work?

A

Delocalised electrons pass through the filament wires and collide with the fixed ions
When the electrons collide with the ions they transfer some energy to the ions
As the pd increases, the number of collisions per second between the electrons and ions increases
As the number of collisions increases, the ions vibrates more
As the temperature increases, the resistance increases

24
Q

What is the rule for resistors in series?

A

The combined resistance is the same of the resistance of all resistors

25
Q

What is the rule for resistors in parallel?

A

The combined resistance is lower than the resistance of the lowest resistor

26
Q

What is the equation for specific heat capacity?

A

Energy = mass x specific heat capacity x change in temp

27
Q

What is a switch?

A

Breaks or completes the circuit

28
Q

What is a cell?

A

Pushes electrons around the circuit

29
Q

What is a battery?

A

Cells joined together

30
Q

What is a lamp?

A

Electricity heats the lamp, lighting it up

31
Q

What is a fuse?

A

Melt and break the circuit if the current is too high

32
Q

What is a diode?

A

In the forward direction it has a low resistance, in the backward direction it has a high resistance.

33
Q

What is a resistor?

A

Controls the size of the current

34
Q

What is a variable resistor?

A

A resistor you can manually change.

35
Q

What is a thermistor?

A

A resistor with a higher resistance in the cold.

36
Q

What is an LDR?

A

A light dependent resistor. When it’s dark it has a higher resistance.

37
Q

What is an LED?

A

A light emitting diode. Same as a diode but it emits light as well.

38
Q

What do you need to remember in RPA 3 Resistance of a wire?

A

Turn off the power supply when not taking the readings to stop getting the wire hot.
Fix the wire to the ruler so that the wire is straight.
Use crocodile clips that make a good contact with the wire.

39
Q

How is the resistance of a wire practical set up?

A

A wire is placed against a ruler at 10cm in a circuit with a voltmeter and ammeter. Record potential difference and current and calculate resistance. Repeat for 20cm, 30cm, 40cm, 50cm etc.

Physics (17 decks)

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