Electronics III Flashcards

1
Q

Electric current is the flow of ________ _______.

A

electric charge

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2
Q

Electric charge is carried by particles such as _________ and _____.

A

electrons

ions

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3
Q

In metals, the charge carriers are negatively charged __________ ________.

A

conduction electrons

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4
Q

Conduction electrons move about inside the ______, repeatedly _________ with each other and the fixed positive _____ of the metal.

A

metal
colliding
ions

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5
Q

Good conductors have many free to move ________ ________.

A

charge carriers

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6
Q

Insulators have few ________ ________.

A

charge carriers

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7
Q

When the ___________ of a semiconductor is _________ more charge carriers are produced and the semiconductor turns from an _________ into a _________.

A

temperature
increased
insulator
conductor

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8
Q

In electric circuits the current is considered to flow out of the ________ terminal of a power supply and into the _________ terminal.

A

positive

negative

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9
Q

A _______ gives each electron a fixed amount of _______.

A

battery

energy

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10
Q

Chemical energy is transformed into ________ potential energy.

A

electrical

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11
Q

______ has to be done to pass electrons through devices like the bulb.

A

Work

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12
Q

Metals and other good conductors have very ____ resistivities.
(e.g. copper = 1.7 x 10 – 8 Ωm)

A

low

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13
Q

Good insulators have very _____ resistivities.

e.g. PVC = 1.0 x 10 + 14 Ωm

A

high

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14
Q

Semiconductors have ___________ resistivities.

e.g. silicon = 2.3 x 10 + 3 Ωm

A

intermediate

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15
Q

Filament lamp, resistance __________ at higher currents due to increasing ___________.

A

increases

temperature

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16
Q

A filament lamp does not obey ______ law.

A

Ohm’s

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17
Q

Thermistor, resistance __________ with increasing temperature.

A

decreases

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18
Q

A thermistor obeys Ohm’s law if the ___________ remains _________.

A

temperature

constant

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19
Q

Metallic conductors, resistance _________ relatively _______ with temperature.

A

increases

slowly

20
Q

Positive ions within a conductor _______ more with increasing temperature

21
Q

Semiconductors, resistance __________ relatively ________ with temperature.

A

decreases

quickly

22
Q

At any junction in a circuit, the total current ________ the junction is equal to the total current _________ the junction.

A

leaving

entering

23
Q

Resistors in series pass the same ________.

24
Q

The total _______ across two resistors, V, is equal to the sum of the individual voltage V1 and V2.
V = V1 + V2

25
The total resistance is always ________ than any of the individual resistances.
greater
26
Resistors in parallel all have the same _______.
voltage
27
The total _______ through the two resistors, I, is equal to the sum of the individual currents I1 and 12. I = I1 + I2
current
28
The total resistance is always ________ than any of the individual resistances.
smaller
29
When an electric ________ flows through an electrical conductor the ___________ of the conductor causes the conductor to be _______.
current resistance heated
30
A car battery has an emf of about _____.
12V
31
A high voltage power supply sometimes has a large protective ________ resistance.
internal
32
Internal resistance limits the _______ that can be supplied to be well below the fatal level of about _____.
current | 50 mA
33
A potential divider consists of ____ or more resistors connected in ______ across a source of ______ potential difference.
two series fixed
34
A potential divider is used in many circuits to control the level of an _______.
output
35
List two examples of using a potential divider
1. Volume control | 2. Automatic light control
36
A capacitor is a device for storing _________ charge.
electrical
37
Most capacitors consist of two parallel __________ (plates) separated by a ________.
conductors | dielectric
38
A dielectric is a material which is a _____ conductor of electricity however it can be _________ by an applied _______ field.
poor polarised electric
39
Uses of capacitors include:
Voltage regulation in power supplies Timing circuits Tuning circuits Back-up power supplies
40
When a voltage is connected to the capacitor _________ flow off one of the ________ plates and onto the ________ plates.
electrons positive negative
41
The ____________ of a capacitor is defined as the _______ stored per unit potential difference change.
capacitance | charge
42
Time constant is the time taken for a capacitor to discharge to _____ of its ______ charge.
0.37 | initial
43
The potential difference across a device is equal to the _____ _____ per unit ______ passing through the device.
work done | charge
44
The electromotive force (emf) of a power supply is equal to the _______ supplied per unit _______ by the power supply.
energy | charge
45
1 volt is equivalent to?
1 joule per coloumb