The ideal diodes ${\mathrm{D}}_1 \mathrm{and} {\mathrm{D}}_2$ are connected in the two branches as shown in the figure.$\left[{\mathrm{R}}_1 = 4\mathrm{\Omega }, {\mathrm{R}}_2 = 5\mathrm{\Omega }, {\mathrm{R}}_3 = 6\mathrm{\Omega }\right]$. Current through the battery is:

             

1.  2A

2.  1A

3.  3A

4.  4A

Zener diodes with breakdown voltage ranging over 2 V — 200 V are commercially available. The breakdown voltage of a Zener diode:

1. Increases with increasing doping concentration

2. Decreases with increasing doping concentration

3. Does not depend on doping concentration

4. May increase or decrease with increasing doping concentration

A Zener diode of breakdown voltage, ${\mathrm{V}}_{\mathrm{Z}}$ = 10 V is used in the given circuit. The current through the load resistor $\left({\mathrm{R}}_{\mathrm{L}}\right)$ is:

1.  10 $\mathrm{\mu A}$

2.  5 $\mathrm{\mu A}$

3.  10 mA

4.  5 mA

The figure shows an n-p-n transistor. Choose the correct statement out of the following.

1.  Collector-base junction, as well as emitter-base junction both, are forward biased.

2.  Collector-base junction, as well as emitter-base junction both, are reverse biased.

3.  Collector-base junction is forward biased and the emitter-base junction is reverse biased.

4.  Collector-base junction is reverse-biased and the emitter-base junction is forward biased.

In the circuit shown in the figure, the current amplification factor ($\mathrm{\beta }$) is 80. Neglecting base-
emitter voltage (${\mathrm{V}}_{\mathrm{BE}}$), calculate the collector current :

1.  0.78 mA

2.  0.96 mA

3.  1.28 mA

4.  2.20 mA

In the circuit shown, if each diode has a forward-biased resistance of 75 $\mathrm{\Omega }$ and infinite resistance in reverse biasing, what will be the values of currents ${\mathrm{i}}_1, {\mathrm{i}}_2, {\mathrm{i}}_3 \mathrm{and} {\mathrm{i}}_4$?

1.  ${\mathrm{i}}_1 = 0.2 \mathrm{A}, {\mathrm{i}}_2 = 0, {\mathrm{i}}_3 = 0.2 \mathrm{A}, {\mathrm{i}}_4 = 0$

2.  ${\mathrm{i}}_1 = 0.26 \mathrm{A}, {\mathrm{i}}_2 = 0, {\mathrm{i}}_3 = 0.26 \mathrm{A}, {\mathrm{i}}_4 = 0$

3.  ${\mathrm{i}}_1 = 0.2 \mathrm{A}, {\mathrm{i}}_2 = 0.07, {\mathrm{i}}_3 = 0.0.7 \mathrm{A}, {\mathrm{i}}_4 = 0.07 \mathrm{A}$

4.  ${\mathrm{i}}_1 = 0.2 \mathrm{A}, {\mathrm{i}}_2 = 0.1, {\mathrm{i}}_3 = 0 \mathrm{A}, {\mathrm{i}}_4 = 0.1 \mathrm{A}$

Doping of a semiconductor (with small traces of impurity atoms) generally changes the resistivity as follows:

1. does not alter

2. increases

3. decreases 

4. may increase or decrease depending on the dopant

Given below are four logic gate symbols (figure). Those for OR, NOR, and NAND are respectively-

1. 

2. 

3. 

4. 

1. 1, 4, 3

2. 4, 1, 2

3. 1, 3, 4

4. 4, 2, 1

In a full-wave rectifier, input ac current has a frequency $\nu$. The output frequency of the current is:

1. $\nu$/2

2. $\nu$

3. 2$\nu$

4. None of these

For the given combination of gates, if the logic states of inputs A, B, C are as follows A=B=C=0, and A =B=1, C=0 then the logic states of output D are:

1. 0, 0

2. 0, 1

3. 1, 0

4. 1, 1