Electronic Devices Chapter-Wise Test 1

Correct answer Carries: 4.

Wrong Answer Carries: -1.

In a p-type semiconductor, the number of holes is related to electrons by:

In a p-type semiconductor, trivalent doping increases holes (majority carriers) significantly over electrons (minority carriers), so \( n_h \gg n_e \), with \( n_e n_h = n_i^2 \).

\( n_h = n_e \)
\( n_h < n_e \)
\( n_h \gg n_e \)
\( n_h = n_e^2 \)
3

The reverse saturation current in a diode is:

The reverse saturation current is nearly constant with voltage (until breakdown), determined by the minority carrier concentration, not the applied reverse voltage magnitude.

Proportional to reverse voltage
Inversely proportional to voltage
Nearly independent of voltage
Zero
3

In a p-n junction under equilibrium, the net current is:

At equilibrium (no bias), diffusion and drift currents balance each other, resulting in zero net current across the p-n junction.

High
Zero
Low
Infinite
2

The electric field in the depletion region of a p-n junction is directed from:

The electric field arises from positive ionized donors on the n-side and negative ionized acceptors on the p-side, directed from the n-side (positive) to the p-side (negative).

P-side to n-side
Negative to positive charge
N-side to p-side
Neutral region to junction
3

In an extrinsic semiconductor, the overall charge neutrality is maintained because:

The charge of additional carriers (electrons in n-type or holes in p-type) is balanced by the equal and opposite charge of ionized dopant cores (positive in n-type, negative in p-type).

Charge of carriers equals that of ionized cores
No recombination occurs
Thermal generation is absent
Drift current cancels diffusion current
1

The number of outer electrons in a Si crystal with \( N \) atoms is:

Each Si atom has 4 valence electrons (2s and 2p). For \( N \) atoms, the total number of outer electrons is \( 4N \), contributing to the covalent bonding in the lattice.

\( 2N \)
\( 8N \)
\( 4N \)
\( N \)
3

The minority carrier injection in a forward-biased diode refers to:

In forward bias, electrons from the n-side cross to the p-side (where they are minority carriers) and holes from the p-side to the n-side, contributing to the diffusion current.

Drift of majority carriers
Diffusion of donor atoms
Crossing of carriers to opposite sides
Recombination in the depletion region
3

The electrical conductivity of a semiconductor is:

Semiconductors have intermediate conductivity (\( 10^5 \) to \( 10^{-6} \, \text{S} \, \text{m}^{-1} \)), between metals (\( 10^2 \) to \( 10^8 \, \text{S} \, \text{m}^{-1} \)) and insulators (\( 10^{-11} \) to \( 10^{-19} \, \text{S} \, \text{m}^{-1} \)).

Higher than metals
Intermediate to metals and insulators
Lower than insulators
Equal to metals
2

The purpose of a capacitor in a rectifier circuit is to:

A capacitor in a rectifier circuit filters out AC ripples by charging to the peak voltage and discharging slowly, smoothing the pulsating output to provide a steadier DC voltage.

Increase current
Smooth the output voltage
Reduce input frequency
Block DC voltage
2

Which of the following is an example of a compound semiconductor?

Compound semiconductors include inorganic materials like CdS, GaAs, and InP, unlike elemental semiconductors (Si, Ge). Among the options, GaAs is a compound semiconductor.

Si
GaAs
Ge
C
2

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