Electronic Devices | Physics JEE previous year questions with Solutions

Q 1 :
Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of photodiode is found to be $(\frac{x}{8}) e V$ . The value of X is (Given, $h = 6.6 \times 10^{- 34} J s, e = 1.6 \times 10^{- 19} C$ ) [2024]

15
11
13
21

1

2

3

4

(A) $Energy bond gap E_{g} is$

$E_{g} = \frac{h c}{λ} = \frac{1240}{λ (in nm)}$

$= \frac{1240}{660} = 1.87 eV$

$or E_{g} = (\frac{15}{8}) eV$

$∴ x = 15$

Q 2 :
The value of net resistance of the network as shown in the given figure is [2024]

$(5 / 2) Ω$
$(30 / 11) Ω$
$(15 / 4) Ω$
$6 Ω$

1

2

3

4

(4)

Diode 2 is in reverse bias, so current will not flow in branch of 2nd diode, So we can assume it to be broken wire.
Diode 1 is in forward bias, so it will behave like conducting wire. The circuit is equivalent to

$R_{e q} = \frac{15 \times 10}{15 + 10} = \frac{15 \times 10}{25} = 6 Ω$

Q 3 :
Which of the diode circuit shows correct biasing used for the measurement of dynamic resistance of p-n junction diode? [2024]

1

2

3

4

(2)

For conduction of current, diode must be in forward biased mode.
So, option (2) is correct.

Q 4 :
The I-V characteristics of an electronic device shown in the figure. The device is: [2024]

a solar cell
a transistor which can be used as an amplifier
a Zener diode which can be used as a voltage regulator
a diode which can be used as a rectifier

1

2

3

4

(3)

It is a theoretical conceptual question. Zener diode used as voltage regulator

Q 5 :
Which of the following circuits is reverse-biased? [2024]

1

2

3

4

(4)

Q 6 :
In the given circuit, the breakdown voltage of the Zener diode is 3.0 V. What is the value of $I_{Z}$ ? [2024]

3.3 mA
5.5 mA
10 mA
7 mA

1

2

3

4

(2)

Breakdown voltage of the Zener diode, $V_{z} = 3 V$

Let potential at $B = 0 V$

Potential at $E (V_{P}) = 10 V$ and $V_{C} = V_{A} = 3 V$

$I = \frac{10 - 3}{1000} = \frac{7}{1000} A and I_{1} = \frac{3}{2000} A$

Also, $I_{Z} + I_{1} = I$

Therefore, $I_{Z} = \frac{7 - 1.5}{1000} = 5.5 mA$

Q 7 :
A Zener diode of breakdown voltage 10V is used as a voltage regulator as shown in the figure. The current through the Zener diode is [2024]

50 mA
0
30 mA
20 mA

1

2

3

4

(3)

$i_{1} = \frac{20 - 10}{200} = \frac{1}{20}$

$i_{2} = \frac{10 - 0}{500} = \frac{1}{50}$

$i_{z} = i_{1} - i_{2} = \frac{1}{20} - \frac{1}{50}$

$= \frac{3}{100} A = 30 mA$

Q 8 :
In the given circuit, the voltage across load resistance $(R_{L})$ is [2024]

8.75 V
9.00 V
8.50 V
14.00 V

1

2

3

4

(1)

${(V_{B})}_{S i} = 0.7 V$

${(V_{B})}_{G e} = 0.3 V$

Voltage drop across both diodes $= 0.7 + 0.3 = 1 V$

So remaining 14 volts will drop across $R_{L} \Rightarrow$

$V_{L} = \frac{2.5}{(1.5 + 2.5)} \times 14 = \frac{2.5}{4} \times 14 volt = 8.75 volt$

Q 9 :
In the given circuit if the power rating of Zener diode is 10 mW, the value of series resistance $R_{s}$ to regulate the input unregulated supply is [2024]

0.5 $kΩ$
10 $Ω$
1 $kΩ$
10 $kΩ$

1

2

3

4

(1)

Potential difference across $R_{s}$

$V_{1} = 8 - 5 = 3 V$

Current through the load resistor

$I = \frac{5}{1 \times 10^{3}} = 5 mA$

Maximum current through Zener diode

$I_{z max.} = \frac{10}{5} = 2 mA$

and minimum current through Zener diode

$I_{z min.} = 0$

$∴$ $I_{s max.} = 5 + 2 = 7 mA$

and $R_{s min} = \frac{V_{1}}{I_{s max.}} = \frac{3}{7} k Ω$

Similarly, $I_{s min.} = 5 mA$

and $R_{s max.} = \frac{V_{1}}{I_{s min.}} = \frac{3}{5} k Ω$

$∴$ $\frac{3}{7} k Ω < R_{s} < \frac{3}{5} k Ω$

Q 10 :
A potential divider circuit is connected with a DC source of 20 V, a light-emitting diode of glow in voltage 1.8 V and a Zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is ____ cm. [2024]

0%

(5)

$V_{P Q} = 3.2 + 1.8 = 5 V$

$And, V_{P R} = 20 V (given)$

Now $\frac{20 V}{20 cm} \times ℓ = 5 V$

Topic Question Set

Q 1 :
Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of photodiode is found to be $(\frac{x}{8}) e V$ . The value of X is (Given, $h = 6.6 \times 10^{- 34} J s, e = 1.6 \times 10^{- 19} C$ ) [2024]

Q 2 :
The value of net resistance of the network as shown in the given figure is [2024]

Q 3 :
Which of the diode circuit shows correct biasing used for the measurement of dynamic resistance of p-n junction diode? [2024]

Q 4 :
The I-V characteristics of an electronic device shown in the figure. The device is: [2024]

Q 5 :
Which of the following circuits is reverse-biased? [2024]

(4)

Q 6 :
In the given circuit, the breakdown voltage of the Zener diode is 3.0 V. What is the value of $I_{Z}$ ? [2024]

Q 7 :
A Zener diode of breakdown voltage 10V is used as a voltage regulator as shown in the figure. The current through the Zener diode is [2024]

Q 8 :
In the given circuit, the voltage across load resistance $(R_{L})$ is [2024]

Q 9 :
In the given circuit if the power rating of Zener diode is 10 mW, the value of series resistance $R_{s}$ to regulate the input unregulated supply is [2024]

Q 10 :
A potential divider circuit is connected with a DC source of 20 V, a light-emitting diode of glow in voltage 1.8 V and a Zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is ____ cm. [2024]

0%

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Topic Question Set

Q 1 : Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of photodiode is found to be (x8)eV. The value of X is (Given, h=6.6×10-34Js,e=1.6×10-19C) [2024]

Q 2 : The value of net resistance of the network as shown in the given figure is [2024]

Q 3 : Which of the diode circuit shows correct biasing used for the measurement of dynamic resistance of p-n junction diode? [2024]

Q 4 : The I-V characteristics of an electronic device shown in the figure. The device is: [2024]

Q 5 : Which of the following circuits is reverse-biased? [2024]

(4)

Q 6 : In the given circuit, the breakdown voltage of the Zener diode is 3.0 V. What is the value of IZ? [2024]

Q 7 : A Zener diode of breakdown voltage 10V is used as a voltage regulator as shown in the figure. The current through the Zener diode is [2024]

Q 8 : In the given circuit, the voltage across load resistance (RL) is [2024]

Q 9 : In the given circuit if the power rating of Zener diode is 10 mW, the value of series resistance Rs to regulate the input unregulated supply is [2024]

Q 10 : A potential divider circuit is connected with a DC source of 20 V, a light-emitting diode of glow in voltage 1.8 V and a Zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is ____ cm. [2024]

0%

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Q 1 :
Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of photodiode is found to be $(\frac{x}{8}) e V$ . The value of X is (Given, $h = 6.6 \times 10^{- 34} J s, e = 1.6 \times 10^{- 19} C$ ) [2024]

Q 2 :
The value of net resistance of the network as shown in the given figure is [2024]

Q 3 :
Which of the diode circuit shows correct biasing used for the measurement of dynamic resistance of p-n junction diode? [2024]

Q 4 :
The I-V characteristics of an electronic device shown in the figure. The device is: [2024]

Q 5 :
Which of the following circuits is reverse-biased? [2024]

Q 6 :
In the given circuit, the breakdown voltage of the Zener diode is 3.0 V. What is the value of $I_{Z}$ ? [2024]

Q 7 :
A Zener diode of breakdown voltage 10V is used as a voltage regulator as shown in the figure. The current through the Zener diode is [2024]

Q 8 :
In the given circuit, the voltage across load resistance $(R_{L})$ is [2024]

Q 9 :
In the given circuit if the power rating of Zener diode is 10 mW, the value of series resistance $R_{s}$ to regulate the input unregulated supply is [2024]

Q 10 :
A potential divider circuit is connected with a DC source of 20 V, a light-emitting diode of glow in voltage 1.8 V and a Zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is ____ cm. [2024]