NEET PhysicsUpdated 19 Oct 2026

Semiconductor Electronics : Materials, Devices and Simple Circuits: NEET PYQs and weightage

Semiconductor Electronics : Materials, Devices and Simple Circuits carries 5.5 of 100 Physics marks in NEET by past-paper share: 42 of the 758 tagged NEET Physics PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 2 of 30 Physics chapters.

Take the 25-question Semiconductor Electronics : Materials, Devices and Simple Circuits test Formula sheet ↓All NEET Physics chapters

5.5/100 Weight in Physics

Exam importance (4/5, by past-paper share)

42 NEET PYQs

334 Practice questions

305 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Physics PYQs in the bank (42 of 758), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Semiconductor Electronics : Materials, Devices and Simple Circuits: formula sheet for NEET

14 formulas, each with when to use it. Copy it onto one page of your notebook: that page is this chapter's handbook.

Mass action law
$n_{e} n_{h} = n_{i}^{2}$
Use it when: any sample in thermal equilibrium (pure or doped) and you need one carrier count from the other
Doped carrier counts
$n-type: n_{e} \approx N_{D}, n_{h} = \frac{n _{i}^{2}}{N _{D}} (so n_{e} ≫ n_{h})$
$p-type: n_{h} \approx N_{A}, n_{e} = \frac{n _{i}^{2}}{N _{A}} (so n_{h} ≫ n_{e}) (holds only when the doping ≫ n_{i})$
Use it when: a doped crystal asks for majority and minority carriers (keep $N_{D}$ , $N_{A}$ and $n_{i}$ in the same unit, e.g. all in $m^{- 3}$ )
Dopant concentration
$N_{D} = (ppm \times 1 0^{- 6}) \times (atoms per m^{3} of Si)$
$e.g. 1 ppm of 5 \times 1 0^{28} m^{- 3} \to 5 \times 1 0^{22} m^{- 3}$
Use it when: doping is given in ppm and you need $N_{D}$ before using entry 2
Intrinsic semiconductor
$n_{e} = n_{h} = n_{i}$
Use it when: the crystal is pure (undoped)
Total current
$I = I_{e} + I_{h}$
Use it when: electron and hole currents are given separately
Dynamic resistance
$r_{d} = \frac{Δ V}{Δ I}$
Use it when: reading diode resistance off a V-I graph between two points (e.g. NCERT Example 14.4: forward $r = 0.1 V /10 mA = 10 Ω$ ; reverse $r = 10 V /1 μ A = 1 0^{7} Ω$ )
Barrier height
$forward bias: V_{0} - V$
$reverse bias: V_{0} + V$
Use it when: asked how bias changes the barrier or the depletion width (forward makes it thinner, reverse makes it wider)
Cut-in (threshold) voltage
$Si \approx 0.7 V$
$Ge \approx 0.2 V$
Use it when: deciding whether a forward-biased diode actually conducts, or subtracting its drop in a circuit
Band gaps
$C (diamond) : 5.4 eV$
$Si : 1.1 eV$
$Ge : 0.7 eV$
$Sn : 0 eV$
Use it when: ranking materials, where $(E_{g})_{C} > (E_{g})_{Si} > (E_{g})_{Ge}$
Classification by Eg
$insulator: E_{g} > 3 eV$
$semiconductor: 0.2 to 3 eV$
$metal: E_{g} \approx 0 (bands overlap)$
Use it when: identifying the material from its band gap
Resistivity
$ρ = \frac{1}{σ}$
$metals: 1 0^{- 8} to 1 0^{- 2} Ω m$
$semiconductors: 1 0^{- 5} to 1 0^{6} Ω m$
$insulators: 1 0^{11} to 1 0^{19} Ω m$
Use it when: classifying a material by conductivity or resistivity
Rectifier output frequency
$half-wave: f_{out} = f_{in}$
$full-wave: f_{out} = 2 f_{in} (50 Hz input gives 100 Hz output)$
Use it when: asked the ripple frequency (full-wave gives one pulse every half cycle)
Filter time constant
$τ = C \cdot R_{L}$
Use it when: judging ripple, since larger $C \cdot R_{L}$ means slower discharge and output closer to the peak voltage
Donor ionisation energy
$Ge :\approx 0.01 eV$
$Si :\approx 0.05 eV$
Use it when: explaining why nearly every donor is ionised at room temperature (compared with $E_{g} \approx 0.7$ or $1.1 eV$ )

Trap

An n-type crystal is not negatively charged, and a p-type crystal is not positively charged. Each extra carrier is balanced by an ionised dopant core of opposite charge, so every doped crystal stays electrically neutral.

How does NEET ask Semiconductor Electronics : Materials, Devices and Simple Circuits?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1PhysicsNEET UG PYQP-N Junction

Try right here · No sign-in

For transistor action, which of the following statements is correct ?

Answer key (B) & worked solution

Correct answer: Option B

For a transistor action, the base junction must be lightly doped so that the base region is very thin.

Q2PhysicsNEET UG PYQP-N Junction

For CE transistor amplifier, the audio signal voltage across the collector resistance of

2 k Ω

is 4 V. If the current amplification factor of transistor is 100 and the base resistance is

1 k Ω

then the input signal voltage is

A20 mV

B30 mV

C15 mV

D10 mV

Answer key (A) & worked solution

Correct answer: Option A

β = 100; V_{0} = 4 V; R_{i} = 1 0^{3} Ω

R_{0} = 2 \times 1 0^{3} Ω, V_{i} = ?

\frac{V _{0}}{V _{i}} = β \frac{R _{0}}{R _{i}} \Rightarrow \frac{4}{V _{i}} = 100 \times \frac{2 \times 10 ^{3}}{10 ^{3}}

\Rightarrow V_{i} = 20 mV

Q3PhysicsNEET UG PYQP-N Junction

A full wave rectifier circuit consists of two p-n junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components remove the ac ripple from the rectified output ?

Ap-n junction diodes

BCapacitor

CLoad resistance

DA centre-tapped transformer

Answer key (B) & worked solution

Correct answer: Option B

Capacitor used to remove AC ripples from Rectifier output.

Q4PhysicsNEET UG PYQP-N Junction

In a common emitter (CE) amplifier having a voltage gain G, the transistor used as transconductance 0.03 mho and current gain 25. If the above transistor is replaced with another one with transconductance 0.02 mho and current gain 20, the voltage gain will be

\frac{2}{3} G

1.5 G

\frac{1}{3} G

\frac{5}{4} G

Answer key (A) & worked solution

Correct answer: Option A

we know that voltage gain,

A_{v} = β \frac{R _{0}}{R _{in}}

= \frac{I _{C}}{I _{B}} \frac{R _{0}}{R _{in}}

= \frac{I _{C} R _{0}}{V _{in}} ..... (V_{in} = I_{B} R_{in})

= g_{m} R_{0}

………(where, gm is the transconductance)

∴ A_{v} \propto g_{m}

∴ \frac{A _{v_{1}}}{A _{v_{2}}} = \frac{g _{m_{1}}}{g _{m 2}} = \frac{0.03}{0.02} = \frac{3}{2}

∴ A v_{2} = \frac{2}{3} A v_{1}

\to ∴ A v_{2} = \frac{2}{3} G

Q5PhysicsNEET UG PYQP-N Junction

The increase in the width of the depletion region in a p-n junction diode is due to:

Aboth forward bias and reverse bias

Bincrease in forward current

Cforward bias only

Dreverse bias only

Answer key (D) & worked solution

Correct answer: Option D

The increase in the width of the depletion region in a p-n junction diode is due to reverse bias only.

Q6PhysicsNEET UG PYQP-N Junction

The barrier potential of a p-n junction depends on: (A) Type of semi conductor material (B) Amount of doping (C) Temperature Which one of the following is correct?

A(B) and (C) only

B(A), (B) and (C)

C(A) and (B) only

D(B) only

Answer key (B) & worked solution

Correct answer: Option B

The barrier potential is depending on the doping level of impurities, It depends on the temperature at which it is operated &which semiconductor material for example Germanium has loosely bound valance electron as compared to the Silicon

Q7PhysicsNEET UG PYQLogic Gates

A logic circuit provides the output Y as per the following truth table: ABY001010101110 The expression for the output Y is:

A . \overset{ˉ}{B} + \overset{ˉ}{A}

\overset{ˉ}{B}

A . B + \overset{ˉ}{A}

Answer key (B) & worked solution

Correct answer: Option B

(\overset{ˉ}{B})

Q8PhysicsNEET UG PYQExtrinsic Semiconductor

For a p-type semiconductor, which of the following statement is true?

AHoles are the majority carriers and trivalent atoms are the dopants.

BHoles are the majority carriers and pentavalent atoms are the dopants.

CElectrons are the majority carriers and pentavalent atoms are the dopants.

DElectrons are the majority carriers and trivalent atoms are the dopants.

Answer key (A) & worked solution

Correct answer: Option A

In p-type semiconductor, an intrinsic semiconductor is doped with trivalent impurities, that creates deficiencies of valence electrons called holes which are majority charge carriers.

Which topics in Semiconductor Electronics : Materials, Devices and Simple Circuits carry the most questions?

All 6 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
P-N Junction	21	134
Logic Gates	14	83
Special Junction Diodes	4	25
Extrinsic Semiconductor	3	38
Intrinsic Semiconductor	0	49
Miscellaneous Examples	0	5

Why does Semiconductor Electronics : Materials, Devices and Simple Circuits show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Semiconductor Electronics : Materials, Devices and Simple Circuits, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

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What happens when you test Semiconductor Electronics : Materials, Devices and Simple Circuits?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

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Chapters either side of Semiconductor Electronics : Materials, Devices and Simple Circuits by weight

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Semiconductor Electronics : Materials, Devices and Simple Circuits: NEET PYQs and weightage

Semiconductor Electronics : Materials, Devices and Simple Circuits: formula sheet for NEET

Mass action law

Doped carrier counts

Dopant concentration

Intrinsic semiconductor

Total current

Dynamic resistance

Barrier height

Cut-in (threshold) voltage

Band gaps

Classification by Eg

Resistivity

Rectifier output frequency

Filter time constant

Donor ionisation energy

How does NEET ask Semiconductor Electronics : Materials, Devices and Simple Circuits?

Which topics in Semiconductor Electronics : Materials, Devices and Simple Circuits carry the most questions?

Why does Semiconductor Electronics : Materials, Devices and Simple Circuits show "–" until you answer 3 questions?

What happens when you test Semiconductor Electronics : Materials, Devices and Simple Circuits?

Chapters either side of Semiconductor Electronics : Materials, Devices and Simple Circuits by weight