When a \(\mathrm{p\text-n}\) junction is formed, the atoms on the \(\mathrm p\)-side are:
1. neutral
2. slightly positive
3. slightly negative
4. all negative
Subtopic:  PN junction |
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The circuit shown in figure is given an input signal \(V_i,\) which varies with time and the corresponding output is \(V_o.\) Then,
1. \(V_o=V_i+E\)
2. \(V_o=V_i-E\)
3. \(V_o=V_i,\) only when \(V_i>E\)
4. \(V_o=V_i,\) only when \(V_i<E\)
Subtopic:  PN junction |
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The voltage \(V_{AB}=20~\text{V}\) at its peak value, and is sinusoidal in time. The current \(i\) (in amperes), when plotted as a function of time, is given by:
(consider the diodes as ideal.)
    
1. 2.
3. 4.
 
Subtopic:  PN junction |
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A voltage \(V_{AB}\) is applied to the left side input and the potential differences \(V_{AX}\) and \(V_{XY}\) are measured. Assume the diodes are ideal i.e., there is no potential difference across the diodes in forward bias. Which of the following is true?

1. \(\text{If}~V_{AB}>0, V_{AX}>0\)
2. \(\text{If}~V_{AB}>0, V_{XY}>0\)
3. \(\text{If}~V_{AB}<0, V_{XY}>0\)
4. \(\text{If}~V_{AB}<0, V_{AX}>0\)
Subtopic:  PN junction |
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What will be the change in the current through the \(5~\text V\) cell if the diode \(D\) is reversed? 
                       
1. No change 
2. Increases by \(0.2~\text A\) 
3. Increases by \(0.3~\text A\)
4. Decreases by \(0.2~\text A \)
Subtopic:  PN junction |
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The current-voltage characteristic of an ideal \(\mathrm{p \text{-}n}\) junction diode is given by the graph as shown in the following figure:

This diode is connected with a resistance of \(5~\Omega\) in series with it as shown below:

Which of the following shows the dependence of the voltage \(V_{AB}\) and the current \(i,\) when the diode is forward-biased?
(\(V_{AB}\) in volt, \(i\) in ampere)
 
1. \(V_{A B}=i\cdot5+0.6\)
2. \(V_{A B}=i\cdot5-0.6\)
3. \(V_{A B}=i\cdot5+(0.6-5)\)
4. \(V_{A B}=i\cdot5+\left(0.6+5\right)\)
Subtopic:  PN junction |
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\(D_1,D_2,D_3\) one identical diodes:    each having a threshold voltage of \(0.6~\text V,\) beyond which the current increases exponentially in forward bias. The diodes don't conduct in reverse bias. \(i\) is the current flowing in at \(A,\) when \(V_{AB}=V_A-V_B>0.\) The variation of \(i\) versus \(V_{AB}\) is best given by:
1. 2.
3. 4.
Subtopic:  PN junction |
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When a \(\mathrm{p\text-n}\) junction is reverse-biased,
1. no current flows at all for any voltage
2. a very small current flows, independent of voltage
3. a small current flows for ordinary voltages, but a very large current may flow if the voltage is increased above a threshold
4. no current flows for ordinary voltage, but a large current flows when voltage exceeds a threshold
Subtopic:  PN junction |
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In the circuit shown in the diagram given below, \(R\) is a small resistor, \(V_i\) is the input voltage between \(A\) & \(B\) while \(V_o\) is the output voltage between \(C\) & \(D\).

Consider the following two statements and mark the correct option.
(I) \(\text{If}~V_i>2~\text{V}, ~\text{then}~V_o = V_i\)
(II) \(\text{If}~V_i<2~\text{V}, ~\text{then}~V_o = 2~\text{V}\)
 
1. (I) is True.
2. (II) is True.
3. (I) and (II) are both True.
4. (I) and (II) are both False.
Subtopic:  PN junction |
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The voltage versus current characteristics of the following circuit is measured: a plot of the current \(i\) versus the voltage drop \(V_{AB}\) is made. Which, of the following graphs, shows the correct variation?
1. 2.
3. 4.
Subtopic:  PN junction |
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