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Physics > Electricity > Flashcards

Electricity Flashcards

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1
Q

What is current?

A

The rate of flow of charge (electrons) past a particular point in a circuit.

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2
Q

What is potential difference?

A

Work done per unit charge.
V = W / Q

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3
Q

What is power?

A

The rate of work done.
P = IV

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4
Q

What does Ohm’s law state?

A

If resistance is constant, then voltage is proportional to current.

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5
Q

What is an ohmic conductor?

A

A conductor that follows Ohm’s law.

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6
Q

What are 4 examples of a non-ohmic conductor?

A
  • Semiconductor diode
  • Filament lamp
  • Thermistor
  • Light-dependant resistor (LDR)
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7
Q

What happens to the resistance of a thermistor when the temperature decreases?

A

Resistance increases

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8
Q

What happens to the resistance of an LDR when the brightness increases?

A

Resistance decreases

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9
Q

What are Kirchhoff’s two laws?

A

Sum of currents flowing into a node = currents leaving the node.

Sum of p.d. in any closed loop = sum of potential drops in that loop.

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10
Q

What happens with voltage and current in a series circuit?

A

Voltage is shared.
Current is the same.

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11
Q

What happens with voltage and current in a parallel circuit?

A

Voltage is the same.
Current is shared.

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12
Q

What is the resistance of an ideal ammeter?

A

Zero

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13
Q

What is the resistance of an ideal voltmeter?

A

Infinite

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14
Q

What is resistivity?

A

(Resistance x Cross-sectional area) / Length

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15
Q

What is a superconductor?

A

If below critical / transitional temperature, resistance and resistivity is zero.

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16
Q

What are some examples of superconductors?

A
  • MRI
  • Particle accelerators
  • Power cables
  • Maglev
17
Q

What does potential divider mean?

A

Input voltage in series circuit is split between components in the same ratio of their resistance to the total resistance.

18
Q

What is a rheostat?

A

A type of variable resistor.

19
Q

What does e.m.f. stand for?

A

Electromotive force

20
Q

What is internal resistance?

A

Resistance of the cell / battery.

21
Q

What is measured on the cell when the circuit switch is open?

A

E.m.f.

22
Q

What is measured on the cell when the circuit switch is closed?

A

Terminal voltage

23
Q

What are lost volts?

A

Voltage lost when current flows through a cell / battery with an internal resistance.

24
Q

What does a semiconductor diode do?

A

Only allows current to flow in one direction.

Physics (10 decks)

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