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AQA A-Level Physics > 5.0 Electricity > Flashcards

5.0 Electricity Flashcards

1
Q

Define electric current

A

The rate of flow of charge

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2
Q

Define potential difference

A

The work done per unit charge

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3
Q

Current - Voltage characteristics for an ohmic conductor

A

Current is directly proportional to voltage, provided temperature remains constant

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4
Q

Current - Voltage characteristics for a semi-conductor diode (forward bias)

A

Current flows once forward bias voltage exceeds threshold voltage

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5
Q

Current - Voltage characteristics for a semi-conductor diode (reverse bias)

A

Current is nearly zero until breakdown voltage, where large reverse current flows

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6
Q

Current - Voltage characteristics for a filament lamp

A

As voltage increases, temperature increases, causing the resistance to increase, and the graph to flatten

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7
Q

I-V graphs of an ohmic conductor

A

linear and passing through the origin

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8
Q

Gradient of the I–V graph for an ohmic conductor

A

it is the reciprocal to the resistance of the conductor

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9
Q

I-V graphs of a semi-conductor diode

A

An exponential rise after or below the threshold voltage or the breakdown voltage respectively

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10
Q

Why does a diode have a threshold voltage?

A

Above a specific voltage is required to overcome the barrier of the junction

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11
Q

I-V graphs for a filament lamp

A

linear through the origin with flattening gradient with increasing absolute voltage

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12
Q

Define ohm’s law

A

Voltage is directly proportional to the current providing constant physical conditions

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13
Q

What is the resistance of an ideal ammeter

A

Zero resistance

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14
Q

What is the resistance of an ideal voltmeter

A

Infinite resistance

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15
Q

Define resistivity

A

A measure of how strongly a material opposes the flow of electric current

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16
Q

What is the effect of temperature on metal conductors

A

Increasing temperature causes more vigorous vibrations in ions, resulting in more electron collisions and so increased resistance

17
Q

What is a thermistor

A

A type of resistor whose resistance depends on its temperature

18
Q

What is the effect of temperature on negative temperature coefficient

A

Increasing temperature releases more free electrons, increasing conductivity and thus reducing resistance

19
Q

What are some applications of thermistors

A

Temperature sensors or resistance - temperature graphs

20
Q

Define superconductivity

A

A property of a material where, below a certain temperature, the resistivity is zero

21
Q

What are some applications of superconductors

A

The production
of strong magnetic fields and the reduction of energy loss
in transmission of electric power

22
Q

What is the total resistance in series

A

The sum of the resistances of the resistors in series

23
Q

What is the total resistance in parallel

A

The sum of the reciprocals is equal to the reciprocal of the total resistance

24
Q

What is the relationship between current in series circuits and cells

A

the current is the same at all points in the circuit

25
Q

What is the relationship between voltage in series circuits and cells

A

the total voltage is the sum of the individual voltages across each component

26
Q

What is the relationship between current in parallel circuits and cells

A

the total current is the sum of the currents through each branch

27
Q

What is the relationship between voltage in parallel circuits and cells

A

the voltage across each branch is the same

28
Q

What is conservation of charge in a DC circuit

A

The total charge entering a junction equals the total charge leaving the junction

29
Q

What is conservation of energy in a DC circuit

A

The total energy supplied by the source is equal to the total energy dissipated in the components of the circuit.

30
Q

What is the use of the potential divider

A

To supply constant or variable
potential difference from a power supply

31
Q

What is electromotive force

A

Electromotive force is the energy provided by a source per unit charge to move the charge through the circuit

32
Q

What is the terminal pd

A

The voltage across the terminals of the source when current flows

33
Q

What is internal resistance

A

Internal resistance is the resistance inside a power source that opposes the flow of current

AQA A-Level Physics (9 decks)

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