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Physics > Current Electricity > Flashcards

Current Electricity Flashcards

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1
Q

What happens when insulating materials are rubbed together?

A

Certain insulating materials become charged when rubbed together.

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2
Q

What is transferred when objects become charged?

A

Electrons are transferred:

  • insulating materials that become positively charged when rubbed lose electrons
  • insulating materials that become negatively charged when rubbed gain electrons
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3
Q

What happens when charges are brought together?

A

Like charges repel.

Unlike charges attract.

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4
Q

What is a cell?

A

It is necessary to push electrons around a complete circuit.

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5
Q

What is a battery?

A

It consists of two or more cells.

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6
Q

What is a switch?

A

It enables the current in a circuit to be be switched on/off.

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7
Q

What is an indicator?

A
  • emits light as a signal when a current passes through it

* light source

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8
Q

What is a diode?

A

It allows current through one directions only.

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9
Q

What is a light-emitting diode (LED)?

A

It emits light when a current passes through it.

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10
Q

What is an ammeter?

A

It is used to measure electric current.

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11
Q

What is a fixed resistor?

A

It limits the current in a circuit.

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12
Q

What is a variable resistor?

A

It allows the current to be varied.

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13
Q

What is a fuse?

A

It melts and therefore breaks the circuit if the current through it it greater than a certain amount.

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14
Q

What is a heater?

A

It transfers electrical energy to heat the surroundings.

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15
Q

What is a voltmeter?

A

It is used to measure potential difference.

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16
Q

What is the size of an electric current?

A

The rate of flow of electric charge.

17
Q

What is electric current?

A

The flow of charge.

18
Q

How can we calculate the size of an electric current?

A

Current (A) = charge flow (C) / time taken (s)

19
Q

What is potential difference?

A

A measure of the work done or energy transferred to the lamp that passes through it.

20
Q

How do we measure the potential difference?

A

Potential difference (V) = work done (J) / charge (C)

21
Q

What is resistance?

A

Resistance (ohms) =potential difference (V) / current (A)

22
Q

What is Ohm’s law?

A

The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.

23
Q

What happens if you reverse the current in a resistor?

A

Reversing the current through a component reverses the potential difference across it.

24
Q

Why is a wire an panic conductor?

A

It’s resistance is constant.

25
Q

What happens to the resistance of a filament bulb as its temperature increases?

A

The resistance increases with increases of the filament temperature.

26
Q

How does the current through a diode depend on on the potential difference across it?

A

In the ‘forward’ direction, the resistance is low.

In the ‘reverse’ direction, the resistance is high.

27
Q

What happens to the resistance of a thermistor as its temperature increases?

A

The resistance decreases if its temperature increases.

28
Q

What happens to the resistance of a light-dependent resistor (LDR) as the light level increases?

A

The resistance decreases if the light intensity on it increases.

29
Q

Where are thermistors and LDRs used?

A

In sensor circuits.

30
Q

What happens to the current in series circuits?

A

The same current passes through components in series with each other.

31
Q

What happens to the potential difference of the voltage supply in series circuits?

A

The total potential difference of the voltage supply in a series circuit is shared between the components.

32
Q

What happens to the potential difference of cells in series circuits?

A

The total potential difference of cells in series is the sum of the potential difference of each cell.

33
Q

How can we find the total resistance of resistors in series?

A

The total resistance of components in series is equal to the sum of the resistance of each component.

34
Q

How can we calculate the current though a resistor in a parallel circuit?

A

Current (A) = potential difference (V) / resistance (ohms)

35
Q

What can we say about the currents in the components in a parallel circuit?

A
  • the total current is the sum of the currents through the separate components
  • the bigger the resistance of a component, the smaller its current is.
36
Q

What can we say about the potential difference across the components in a parallel circuit?

A

The potential difference is the same across each component.

Physics (5 decks)

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