Which of the following is correct for the Zener diode?
(a) It acts as a voltage regulator.
(b) It is used in forward bias.
(c) It is used in reverse bias.
(d) It is used as a switch in series.

Choose the correct option from the given ones:
1. (a) and (d)
2. (b) and (c)
3. (a) and (c)
4. (b) and (d)

 
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The advantages of LEDs are:

1. long lifespan
2. quick on-off switching
3. low operating voltage
4. all of the above
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A Zener diode is specified having a breakdown voltage of \(8.1~\text{V}\) with a maximum power dissipation of \(346~\text{mW}\). The maximum current that diode can handle is: 
1. \(34~\text{mA}\) 
2. \(42.7~\text{mA}\) 
3. \(36.2~\text{mA}\)
4. \(52.6~\text{mA}\)
Subtopic:  Applications of PN junction |
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The voltage across \(AB,\) \(V_{AB}=6\) to \(7~\text V,\) and it can vary. A \(5~\text V\)-Zener diode is to be connected between \(P,Q\) so that the voltage across the \(100~\Omega\) resistance is maintained at that value.
                   
After the \(5~\text V\)-Zener diode(s) is/are properly connected, the current through the \(100~\Omega\) resistor is:
1. \(5~\text A\)
2. \(0.05~\text A\)
3. \(0.025~\text A\)
4. \(0.1~\text A\)
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In the given circuit, the value of current, \(I_L\) is:
(where \(R_L = 1~\text{k} \Omega\))
     
1. \(2~\text{mA}\)
2. \(4~\text{mA}\)
3. \(3~\text{mA}\)
4. \(5~\text{mA}\)
Subtopic:  Applications of PN junction |
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If a semiconductor photodiode can detect a photon with a maximum wavelength of \(400~\text{nm},\) then the energy of its band gap is:
(take Planck’s constant \(h=6.63 \times 10^{-34} \text { J-s }\) and speed of light \(c=3 \times 10^8\) m/s)
1. \(3.1~\text{eV}\)
2. \(1.1~\text{eV}\)
3. \(2.0~\text{eV}\)
4. \(1.5~\text{eV}\)

Subtopic:  Applications of PN junction |
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In the voltage regulator circuit shown below, the reverse breakdown voltage of the Zener diode is \(3~\text{V}.\)Then the current through the Zener diode is:
         
1. \(7~\text{mA}\)
2. \(1.5~\text{mA}\)
3. \(5.5~\text{mA}\)
4. \(10~\text{mA}\)
Subtopic:  Applications of PN junction |
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An LED is:
1. a \(\mathrm{p}\)-doped silicon that emits light
2. a \(\mathrm{n}\)-doped silicon that emits light
3. a \(\mathrm{p \text-n}\) diode that emits light
4. a transistor that absorbs light
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Which color LED contains the smallest band-gap?
1. Red 
2. Green 
3. Yellow 
4. Blue
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The \(V\text-I\) characteristics of a solar cell is shown in the figure. The points \(\mathrm{A}\) and \(\mathrm{B}\) are respectively called:
              
1. open circuit voltage; short circuit current
2. open circuit voltage; open circuit current
3. short circuit voltage; short circuit current
4. short circuit voltage; open circuit current
Subtopic:  Applications of PN junction |
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