Blog Log in Get Started Free

NEET Practice Questions (MCQs) with Answers & Solutions

Practice free NEET NEET multiple-choice questions online with instant answers and detailed explanations. No login required.

All Physics Chemistry Botany Zoology

Language English हिंदी

● ● ● ● ●

Choose the correct statement

When we heat a semiconductor its resistance increases

When we heat a semiconductor its resistance decreases

When we cool a semiconductor to 0 K then it becomes super conductor

Resistance of a semiconductor is independent of temperature

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(b) With rise in temperature, conductivity of semiconductor increases while resistance decreases.

● ● ● ● ●

Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers would be

Positively charged

Negatively charged

Positively charged or negatively charged depending upon the type of impurity that has been added

Electrically neutral

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(d) Extrinsic semiconductor (N-type or P-type) are neutral.

● ● ● ● ●

If $n_{e}$ and $v_{d}$ be the number of electrons and drift velocity in a semiconductor. When the temperature is increased

$n_{e}$ increases and $v_{d}$ decreases

$n_{e}$ decreases and $v_{d}$ increases

Both $n_{e}$ and $v_{d}$ increases

Both $n_{e}$ and $v_{d}$ decreases

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) Because $v_{d} = \frac{I}{(n_{e}) eA}$

● ● ● ● ●

The energy gap of silicon is 1.14 eV. The maximum wavelength at which silicon will begin absorbing energy is

10888 Å

1088.8 Å

108.88 Å

10.888 Å

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) $λ_{\max} = \frac{hc}{E} = \frac{6.6 \times 10^{- 34} \times 3 \times 10^{8}}{1.14 \times 1.6 \times 10^{- 19}} = 10888$ Å

● ● ● ● ●

The mobility of free electrons is greater than that of free holes because

They carry negative charge

They are light

They mutually collide less

They require low energy to continue their motion

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(d) Electrons require low energy for mobility as they suffer low resistance during their motion as compared to holes.

● ● ● ● ●

In a semiconducting material, the mobilities of electrons and holes are $μ_{e}$ and $μ_{h}$ respectively. Which of the following is true?

$μ_{e}$ > $μ_{h}$

$μ_{e}$ < $μ_{h}$

$μ_{e}$ = $μ_{h}$

$μ_{e}$ <0; $μ_{h}$ >0

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) Because electrons needed less energy to move.

● ● ● ● ●

A silicon speciman is made into a P-type semi-conductor by dopping, on an average, one Indium atom per $5 \times 10^{7}$ silicon atoms. If the number density of atoms in the silicon specimen is $5 \times 10^{28} atoms / m^{3}$ then the number of acceptor atoms in silicon per cubic centimetre will be

$2.5 \times 10^{30} atoms / {cm}^{3}$

$1.0 \times 10^{13} atoms / {cm}^{3}$

$1.0 \times 10^{15} atoms / {cm}^{3}$

$2.5 \times 10^{36} atoms / {cm}^{3}$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(c) Number density of atoms in silicon specimen = $5 \times 10^{28} atom / m^{3}$ = $5 \times 10^{22} atom / {cm}^{3}$ . Since one atom of indium is doped in $5 \times 10^{7}$ Si atom. So number of indium atoms doped per ${cm}^{3}$ of silicon.

$n = \frac{5 \times 10^{22}}{5 \times 10^{7}} = 1 \times 10^{15} atom / {cm}^{3}$

● ● ● ● ●

The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature

Decreases exponentially with increasing band gap

Increases exponentially with increasing band gap

Decreases with increasing temperature

Is independent of the temperature and the band gap

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) The probability of electrons to be found in the conduction band of an intrinsic semiconductor

$P (E) = \frac{1}{1 + e^{\frac{(E - E_{F})}{kT}}}$ ; where k = Boltzmann's constant
Hence, at a finite temperature, the probability decreases exponentially with increasing band gap.

● ● ● ● ●

The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is 10 V. The dc component of the output voltage is

$10 / \sqrt{2}$ V

$10 / π$ V

10 V

$20 / π$ V

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(b) In half wave rectifier $V_{dc} = \frac{V_{0}}{π} = \frac{10}{π}$

● ● ● ● ●

A transistor is used as an amplifier in CB mode with a load resistance of 5 k $Ω$ . The current gain of the amplifier is 0.98 and the input resistance is 70 $Ω$ , the voltage gain and power gain respectively are :

70, 68.6

80, 75.6

60, 66.6

90, 96.6

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

(a) In common base mode $α$ = 0.98, R = 5 k $Ω$ , $R_{in}$ = 70 $Ω$
$∴$ voltage gain $A_{v} = α \times \frac{R}{R_{in}} = 0.98 \times \frac{5 \times 10^{3}}{70} = 70$
Power gain = Current gain $\times$ Voltage gain
= 0.98 $\times$ 70 = 68.6

Ready to ace NEET?

Free access · No credit card required

Browse All Questions Create Free Account

Frequently Asked Questions

Yes. You can attempt every NEET question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.

No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.

The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.