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Physics > P2 Physics Top 36 > Flashcards

P2 Physics Top 36 Flashcards

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1
Q

What is the definition of current?

A

Current is the rate of flow of charge

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2
Q

State an equation that links current, charge flow and time. Write down the units of each.

A

Q = I × t
Q – Charge(coulombs) (C)
I – Current (amps) (A)
T – Time (seconds) (s)

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3
Q

What is the equation that links potential difference, current, and resistance?

A

V = I × R

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4
Q

What is an IV characteristic?

A

A graph showing how the current flowing through a component changes is the potential difference across it changes

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5
Q

Explain what happens in a resistor IV graph.

A

Current increases in proportion to voltage in a directly proportional way

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6
Q

Explain what happens in a filament lamp IV graph

A

As voltage increases, the bulb gets hotter and resistance increases

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7
Q

Explain what happens in a diode IV graph

A

A diode only lets current go in One Direction so it has high resistance in the other direction

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8
Q

What happens to the resistance of a filament lamp as the current increases and why?

A

Temperature increases as current increase increases so resistance increases

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9
Q

What is the effect on current of increasing resistance?

A

As resistance increases current decreases

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10
Q

What happens to the resistance of a thermistor as it gets hot

A

As temperature increases resistance increases

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11
Q

What happens to the resistance of an LDR if there is more light?

A

As light increases resistance decrease

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12
Q

True or false? Potential difference is shared between components in a series circuit.

A

True

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13
Q

What is the rule for current in a series circuit

A

Current is the same everywhere

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14
Q

How does the overall resistance of a circuit change when a resistor is added in parallel?

A

Resistance decreases as more components are added

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15
Q

What is the potential difference and the frequency of UK mains supply

A

230 V and 50 Hz

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16
Q

Name and give the colours of the three wires in a three core cable

A

Earth- green and yellow, live- brown, neutral- blue

17
Q

Describe the useful energy transfer occurs for a battery powered fan

A

Energy transferred electrically from the battery of a handheld fan to the kinetic energy store of the fans motor

18
Q

State the equations that can be used to calculate electrical power

A

Power = current × potential difference (P= I × V)
Power = current² × resistance (P= I² × R)

19
Q

How are step up Transformers used in the national grid?

A

Step up Transformers are used to increase the voltage/potential difference

20
Q

How are stepdown Transformers used in the national grid?

A

Step down Transformers reduce the voltage/potential difference to safe levels

21
Q

Describe how you would investigate how the length of wire affects resistance

A
  • Set up the circuit with a power supply, an ammeter to measure current, a voltmeter to measure voltage, and a wire of variable length.
  • Connect the wire in series with the ammeter and the power supply.
  • Measure resistance for different lengths of the wire using ohms law
  • Measure the voltage across the wire using the voltmeter and the current through the wire using the ammeter.
  • Record data in a table or graph to show the length of the wire, the measured voltage, the measured current, and the calculated resistance.
  • Analyse results and plot a graph of resistance (R) against length (L) of the wire and look at the trend to determine how resistance changes with length.
22
Q

Describe an experiment to investigate how adding resistors in series and parallel affects the total resistance in a circuit

A
  • Set up the series circuit with a power supply, an ammeter, and multiple resistors in series.
  • Measure the total resistance by adding the individual resistances together
  • Measure the total voltage across the series circuit with voltmeter and use the ammeter to measure the current.
  • Set up the circuit for parallel by connecting the same resistors in parallel and then also measure the total voltage and current again
  • Calculate total resistance in parallel and calculate the total resistance using the measured values
  • Record data in a table or graph to compare the total resistance in series and parallel
  • Analyse how the total resistance changes with the arrangement of resistors.
23
Q

Explain how an LDR works

A

As light intensity increases, resistance decreases

24
Q

Explain how a thermistor works

A

As temperature increases, resistance decreases

25
Q

Define potential difference

A

Energy carried by electrons

26
Q

Define resistance

A

Measure of opposition flow to an electrical circuit

27
Q

What is the order of the national grid beginning with power station?

A

Power station, step up transformer, pylons, step down transformer, consumers

28
Q

Where are step up transformers found?

A

After the power plant, before entering pylons

29
Q

Where are step down Transformers found

A

After leaving pylons, before entering consumers

30
Q

2000 J of energy is transferred over three seconds, what is the power?

A

P = 2000/3
P = 666.7 W

31
Q

14,000 W of power is used on a device over a period of two hours. How much energy is transferred?

A

14,000 = E/120
E =14,000/120
E = 116.6 J

32
Q

A 900 W microwave is cooking some chicken, 340,000 J of energy is needed to cook the chicken. How much time will it be in the microwave?

A

P = e/t
900 = 340,000/t
t = 340,000/900
t = 377.8 s

33
Q

A current of 3 A was passed into a battery over a period of five hours. How much charge was transferred?

A

Q = 3×300
Q = 900 C

34
Q

A charge of 18,000 C was transferred passing with a current of 5 A. How long did the current flow for?

A

18,000 = 5 × T
T = 18,000/5
T = 3600s

35
Q

A six ohms resistor has a occur passing through of 4 A. What was the potential difference over the resistor?

A

V = 4×6
V = 20 V

36
Q

A resistor of two ohms has a potential difference of 4 V. How much current is being passed?

A

4 = I×2
I = 4/2
I = 2A

Physics (2 decks)

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