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Physics > P4: Electric circuits > Flashcards

P4: Electric circuits Flashcards

1
Q

What is current

A

Flow of charge in a circuit

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2
Q

What is current measured in

A

Amperes

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3
Q

How do we calculate charge flow

A

Current X Time

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4
Q

How can an electric charge be able to flow

A

There must be a potential difference source and a closed or complete circuit.

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5
Q

What is an electrical conductor

A

A material that allows electric current (flow of charge) to pass through. It conducts electricity

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6
Q

What is an electrical insulator

A

A material that doesn’t allow electric current (flow of charge) to pass through. It doesn’t conduct electricity. It has no delocalised electrons

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7
Q

What is electric current through a metal

A

Flow of delocalised electrons

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8
Q

What is potential difference (voltage)

A

The pushing force of current in a circuit

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9
Q

What is voltage measured in

A

Volts

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10
Q

What do we use to measure current

A

Ammeter

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11
Q

What do we use to measure voltage

A

Voltmeter

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12
Q

What is resistance

A

The slowing force of current in a circuit

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13
Q

What is resistance measured in

A

Ohms

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14
Q

What is the effect linking voltage, current and resistance

A

If voltage is increased, current is increased and resistance is constant. To measure resistance of a component, measure the voltage of a component. The longer the wire, the higher the resistance.

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15
Q

What is the equation to work out resistance

A

Voltage/Current

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16
Q

What are the results if we plot a current voltage graph

A

As the voltage is increased, the current is increased.

It also obeys Ohms Law as it states it is a straight line. The slope of the graph is 1/resistance. It shows that the resistance is constant.

17
Q

What are the results if we plot a filament bulb graph

A

The gradient will decrease at larger potential differences. When current through a filament (thin wire) lamp increases, temperature of lamp increases. This increases resistance of the lamp and causes a curve in the graph

18
Q

What is a diode

A

Diodes are components that allow current to flow in one direction

19
Q

What is a rectifier

A

Rectifiers are components that turn an alternating current into a direct current.

Diodes act as rectifiers as they break the alternating current when changing direction

20
Q

What is a thermistor

A

A component where resistance changes with its temperature.

Usually increasing temperature decreases resistance. Thermistors can be used to turn a heater off when a house reaches a certain temperature

21
Q

What is an LDR

A

Light Dependent Resistor. The resistance changes with light intensity. An LDR can switch lights on when its dark

22
Q

What does the energy source do in an electric circuit

A

Provides electrical energy to a bulb which radiates that energy as light and heat energy

23
Q

What is an ohmic conductor

A

A conductor that obeys Ohm’s Law. It has a constant resistance. Current through an ohmic conductor (at constant temperature) is directly proportional to potential difference across a resistor

24
Q

What is a series circuit

A

A circuit with all its components connected on the same line as each other. In series, current is the same.

25
Q

How do we calculate resistance in a series circuit

A

Add up all of the individual resistors together

26
Q

How is a battery made

A

Combining cells

27
Q

How do we calculate voltage in a series circuit

A

Add up all of the individual voltages together

28
Q

What is a parallel circuit

A

A circuit that has its components connected in separate branches of wires to the energy source. In parallel, voltage is the same across everywhere.

29
Q

How does current work and how do we work it out in parallel

A

Current through battery is larger than all of the individual currents. To work out the total current, add all of them up individually. It should equal the total current in the supply.

30
Q

How do we work out the resistance in parallel

A

The combined resistance of two resistors in parallel is less then the resistance of the resistors individually. To work out the total resistance, deduct the individual resistors together

31
Q

What happens to the lamp in parallel

A

Each lamp can switched off or on separately. However if 1 lamp breaks, current can still flow through the others.

32
Q

What is the equation for power

A

Energy transfer/Time

33
Q

What is the other equation for power

A

Current X Current X Resistance

34
Q

What are two other equations for power

A

Voltage x Current

Current X Current X Resistance

35
Q

What is Ohms Law?

A

Current through an ohmic conductor is directly proportional to the voltage across the resistor. This means the resistance remains constant as the current changes

Physics (7 decks)

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