Test: Semiconductor Electronics: Materials, Devices & Simple Circuits- Assertion & Reason Type Questions


10 Questions MCQ Test Physics Class 12 | Test: Semiconductor Electronics: Materials, Devices & Simple Circuits- Assertion & Reason Type Questions


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Attempt Test: Semiconductor Electronics: Materials, Devices & Simple Circuits- Assertion & Reason Type Questions | 10 questions in 20 minutes | Mock test for Class 12 preparation | Free important questions MCQ to study Physics Class 12 for Class 12 Exam | Download free PDF with solutions
QUESTION: 1

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): The resistivity of a semiconductor decreases with temperature.

Reason (R): The atoms of a semiconductor vibrate with larger amplitude at higher temperature there by increasing it's resistivity.

Solution: Resistivity of semiconductors decreases with temperature. So, assertion is true. Electrons from valence band jumps to conduction band with rise of temperature and hence the resistivity decreases. Hence, the reason is also false.
QUESTION: 2

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Silicon is preferred over Germanium for making semiconductor devices.

Reason (R): The energy gap of Germanium is more than the energy gap of Silicon.

Solution: Silicon is preferred over Germanium for making semiconductor devices. The assertion is true.

The energy gap of Germanium is about 0.7 eV, where as the energy gap of Silicon is 1.1 eV. Hence, the reason is false.

QUESTION: 3

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Zener diode is used as a voltage regulator.

Reason (R): Zener diode operated in reverse biased condition.

Solution: Zener diode is used as a voltage regulator in reverse biased condition. So, both assertion and reason are true, but the reason does not explain the assertion.
QUESTION: 4

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): When diode is used as a rectifier, its specified reverse breakdown voltage should not be exceeded.

Reason (R): When p-n junction diode crosses the reverse break down voltage, it get destroyed.

Solution: When a diode is used as a rectifier, it has to face both positive and negative halves of the alternating voltage.
QUESTION: 5

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): The number of electrons in a p-type silicon semiconductor is less than the number of electrons in intrinsic silicon semiconductor at room temperature.

Reason (R): It is due to law of mass action.

Solution: In p-type semiconductor, electron is the minority charge carrier. So, number of electrons is less than the number of electrons in intrinsic semiconductor. So the assertion is true. According to the law of mass action = n2i = ne × nh. In intrinsic semiconductor, ne = nh . So in p-type semiconductor, ne < nh. So reason is also true.
QUESTION: 6

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): As the temperature of a semiconductor increases, its resistance decreases.

Reason (R): The energy gap between conduction band and valence band is small.

Solution: As temperature rises, the electrons of valence band sufficient energy and jump to the conduction band. Thus, the resistivity decreases. So the assertion is true.

In semiconductors the energy gap between conduction band and valence band is small. Due to this, the electrons in the conduction band can gain sufficient thermal energy with temperature rise and can easily jump across the small energy gap to reach the conduction band. Thus, conductivity increases and resistance decreases.

QUESTION: 7

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Semiconductors do not obey Ohm's law.

Reason (R): V-I characteristic of semiconductors is linear.

Solution: Semiconductors do not obey Ohm's law. So the assertion is true. V-I characteristic of a semiconductor is non-linear. Hence the reason is false.
QUESTION: 8

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Ideal diode shows zero resistance in forward bias and infinite resistance in reverse bias.

Reason (R): Depletion region of a p-n junction diode extends in reverse bias and contracts in reverse bias.

Solution: In forward bias condition, the depletion region of a p-n junction diode contracts and the majority charge carriers can cross the junction very easily. So, the resistance becomes low (ideally 0).

In reverse bias condition, the depletion region of p-n junction diode expands and the majority charge carriers cannot cross the junction. So, the resistance increases (ideally ∞).

So, the assertion and reason both are true and reason explains the assertion.

QUESTION: 9

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): When a p-n junction diode is reverse biased, a feeble reverse current flows known as reverse saturation current.

Reason (R): In reverse bias condition, the minority carries can cross the junction.

Solution: When a p-n junction is reverse biased, then the majority charge carriers cannot cross the junction. So, no forward current flows. But in reverse direction, a feeble current flows which is known as reverse saturation current. So, the assertion is true.

In p-side there are few electrons as minority charge carrier and in n-side, there are few holes as minority charge carriers. In reverse bias condition, the holes at n-side feel a pull exerted by the negative polarity of the voltage source connected to the p-side. Similarly, the electrons at p-side feel a pull exerted by the positive polarity of the voltage source connected to the n-side. So, these minority carries now can cross the junction and give rise to a feeble current in the opposite direction. Hence, the reason is also true and it explains the assertion.

QUESTION: 10

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): In a semiconductor, the conduction electrons have a higher mobility than holes.

Reason (R): The electrons experience fewer collisions.

Solution: Electrons experience many collisions. The mobility of electrons is more because they require less energy to move, not because they are lighter.
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