Current electricity (13) Flashcards Preview

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Flashcards in Current electricity (13) Deck (10)
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1
Q

Resistance, R

A

defined by the equation R=V/I . Measured in ohms, Ω. The resistance of a conductor is the opposition of the conductor to electric current flowing through it.

2
Q

Electrolyte

A

a conducting solution, usually containing positive and negative salt ions dissolved in water.

3
Q

Electromotive force (emf)

A

the amount of electrical work done per unit charge by a power supply such as a cell in an electrical circuit. The power supply transfers the other forms of energy, such as chemical energy into electrical energy. The unit is the volt, V.

4
Q

Superconductor

A

a material whose resistance drops to zero below a specific temperature, called the critical temperature.

5
Q

Electrical characteristic

A

a graph (usually I-V) that illustrates the electrical behaviour of the component.

6
Q

Ohmic conductor

A

the current flowing through an ohmic conductor is proportional to the pd applied across it.

7
Q

Non-ohmic

A

a non-ohmic component is a component that does not obey Ohm’s law; i.e. the current is not proportional to the potential difference applied across it.

8
Q

Thermistor

A

a component whose resistance varies with temperature. Many thermistors used in electrical circuits have a negative temperature coefficient (ntc), meaning that their resistance decreases with increasing temperature.

9
Q

Intrinsic

A

an intrinsic property of a material is a property of the material itself, independent of other factors. E.g. resistivity.

10
Q

Resistivity

A

the resistivity of a substance is the intrinsic resistance of the material that the substance is made from; it is independent of the dimensions of the substance. Resistivity also varies with temperature, although the resistivity of metals changes only gradually with temperature.