Diodes Flashcards

1
Q

Approximate thickness of depletion layer?

A

10^-6 m
Or
1 micrometer

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2
Q

Potential barrier (Vb) for Germanium diode

A

0.3V

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3
Q

Potential barrier for silicon diode

A

0.7V

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4
Q

Barrier electric field is of the order?

A

10^5 Vm-1

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5
Q

For forward biasing forward current is of the order

A

mA

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6
Q

For reverse biasing the order of reverse current is

A

MicroAmpere

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7
Q

What is the Richardson-Dushman Equation for half wave rectifier?

A

J= A x t^2 x e^(W/kT)

Where:
W- work function
k- Boltzmann’s constant
A-constant for pure metals= 60 A/cm2

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8
Q

Child Langmuir Law

A

For a space charge limited current :-

L~ (V)^3/2

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9
Q

Vrms =?

A

Vpeak/2

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10
Q

Vdc =? (For half wave rectifier)

A

Vpeak/||

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11
Q

Vpeak =?

A

2xVrms = ||xVdc

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12
Q

Vdc for full wave rectifier ?

A

2xVpeak/||

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13
Q

Ripple?

A

AC components present in rectifier’s outputs

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14
Q

Ripple factor (r)?

A

Measurement of AC components in a rectifier’s output

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15
Q

Ripple factor(r) for half wave rectifier

A

1.21

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16
Q

Ripple factor for full wave rectifier

17
Q

In reverse biased mode how does the LED work

A

It works like a normal diode

18
Q

LED’s light emitting intensity is

A

Directly Proportional to forward current

19
Q

Photodiode materials?

A
Cadmium Sulphide (CdS)
Serilium (Se)
Zinc Sulphide (ZnS)
20
Q

For a photodiode Energy of incident light photon must be

A

Greater than the forbidden gap energy

21
Q

In Solar cells one of the semiconductors is made extremely small

A

So that solar radiation falling on it passes to the junction without any absorption

22
Q

Popularly used solar cells?

A
Nickel-Cadmium             (Ni-Cd)cell
Lead Sulphide(PbS) cell
23
Q

Width of depletion zone is

A

Dependant of dopant densities

24
Q

On forward biasing a p-n junction

A

Number of donors in n-side increase

25
On forward biasing the width of depletion layer
Decreases
26
On reverse biasing the width of depletion layer
Increases
27
Photodiode is
Reverse biased and heavily doped
28
LED is
Forward biased
29
Materials used to make LED diodes
GaAs | GaP