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Module 4 - Electronic Fundamentals B1 > Diode Characteristics and Properties > Flashcards

Diode Characteristics and Properties Flashcards

1
Q

What are diodes?

A

Semiconductors that allow the flow of electricity one way

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2
Q

To check forward resistance of a diode, the positive terminal lead of a multimeter should be connected to…

A

The anode

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3
Q

What gives the colour of an LED?

A

The active element

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4
Q

An atom with 5 electrons in its outer shell is part of P or N type material?

A

N type material

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5
Q

What is an SCR?

A

Silicon controlled rectifier (thyristor)

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6
Q

What are the properties of a thyristor?

A
  • 3 terminal device used for switching
  • turned on by a positive voltage at the gate
  • silicon based
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7
Q

What component is used to turn AC to DV?

  • Diode
  • Thyristor
  • Transistor
A

Diode

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8
Q

What type of diode gives off light photons when forward biased?

A

LED

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9
Q

To function, how much voltage does a germanium diode require?

A

0.3V forward biased

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10
Q

To function, how much voltage does a silicon diode require?

A

0.7V forward biased

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11
Q

What is a zener diode used for?

A

Voltage control.

It stabilises voltage at a predetermined level

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12
Q

When a diode is forward biased, what is the current flow due to?

A

The majority carriers (electrons and holes)

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13
Q

An atom with 5 electrons in its outer shell is part of what?

A

An N-type material.
It is pentavalent and will provide an extra free electron making the material N type.

Phosphor and Arsenic are examples

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14
Q

In a PN junction, what is the depletion region?

A

A depletion/lack of free electrons and holes in a vicinity of the junction.

It is reduced when the junction is forward biased

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15
Q

How is an SCR turned on?

A

A positive voltage at the gate

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16
Q

In a semiconductor junction diode, where are the electrons minority carriers?

A

Within the P region

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17
Q

If a rectifier circuit is designed to convert positive and negative cycles into DC output, what is the process called?

A

Full-wave rectification

18
Q

Which type of diode (silicon or germanium) has the lower forward bias voltage?

A

Germanium diode

19
Q

What are indium and aluminium used for in diodes?

A

They are a neutral semiconductor

20
Q

How can the conductivity of an intrinsic semiconductor be improved?

A

By doping the materials

21
Q

What are the electrodes of an SCR?

A
  • gate
  • anode
  • cathode
22
Q

How is an SCR switched off?

A
  • Removing the source potential/reducing it below minimum holding current
  • Reversing the current
23
Q

A zener diode is reverse biased. When forward biased, what happens to a zener diode?

A

It will conduct like an ordinary rectifier diode.

24
Q

When light falls onto a photo sensitive diode, it causes the resistance to…

A

Decrease

25
Q

What is an intrinsic material?

A

A pure material

26
Q

What is the typical voltage drop across an LED?

A

1.6V to 2.4V

Around 2V

27
Q

A thyristor has high resistance when…

A

Switched off

28
Q

A zener diode has what characteristics of voltage and current?

A
  • Constant voltage

- variable current

29
Q

What is the purpose of using two diodes in parallel?

A

Prevents damage by excessive current

Voltage remains the same, current is split.

30
Q

What is antimony?

A

A donor material

31
Q

When will a photodiode increase its resistance?

A

When less light falls on it

32
Q

Do photodiodes work in forward or reverse bias?

A

Reverse

33
Q

In a forward bias diode, current is carried by…

A

Both majority and minority carriers, but mainly majority. (Electrons and holes)

Reverse bias is minority only.

34
Q

What would a serviceable diode read when a multimetrer is connected to it?

A

0.7V when forward biased

35
Q

What is the maximum reverse voltage for any LED?

A

5V

36
Q

What is a silicon diode used for?

A

Rectification

37
Q

What is a germanium diode used for?

A

Demodulation

38
Q

What is a diode connected across a relay coil used for?

A

Dissipate coil spikes on switch off

39
Q

How many diodes are used in a full wave 3-phase rectifier circuit?

A

6 diodes

40
Q

How does a photodiode operate?

A

Reverse bias conditions.

  • leaking current increasing with light increasing
  • resistance
41
Q

Reverse bias systems will _______ the potential barrier.

A

Increase

Module 4 - Electronic Fundamentals B1 (5 decks)

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