Electronic Devices Chapter-Wise Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

At absolute zero (0 K), an intrinsic semiconductor behaves as:

At 0 K, no thermal energy is available to excite electrons across the energy gap, so an intrinsic semiconductor has no free carriers and acts like an insulator.

Conductor
Semiconductor
Insulator
Superconductor
3

The output of a half-wave rectifier without a filter is:

A half-wave rectifier outputs only the positive half-cycles of the AC input, producing a pulsating DC voltage without a steady value unless filtered.

Steady DC
Pure AC
Zero voltage
Pulsating DC
4

The ripple in a rectifier output is reduced by using:

A capacitor filter smooths the pulsating DC output by charging during peaks and discharging during troughs, reducing AC ripples to provide a steadier DC voltage.

Transformer
Capacitor
Resistor
Diode
2

The dynamic resistance of a diode is defined as:

Dynamic resistance (\( r_d \)) is the ratio of a small change in voltage (\( \Delta V \)) to the corresponding small change in current (\( \Delta I \)), i.e., \( r_d = \Delta V / \Delta I \), reflecting the diode's behavior under small signal variations.

\( \Delta I / \Delta V \)
\( V / I \)
\( I / V \)
\( \Delta V / \Delta I \)
4

In an n-type semiconductor, the charge of the donor ion core is:

A pentavalent donor (e.g., P) donates one electron, leaving a positively charged ion core (+q) after ionization, balanced by the free electron’s negative charge.

Negative
Neutral
Positive
Zero
3

The reverse saturation current in a p-n junction diode is typically in the order of:

The reverse saturation current, due to minority carrier drift, is very small and typically in the microampere (\( \mu \text{A} \)) range, independent of applied voltage until breakdown.

Milliampere (mA)
Ampere (A)
Microampere (\( \mu \text{A} \))
Nanoampere (nA)
3

The majority carriers in an n-type semiconductor are:

In an n-type semiconductor, pentavalent doping increases the number of conduction electrons, making them the majority carriers, while holes are minority carriers (\( n_e \gg n_h \)).

Holes
Positive ions
Electrons
Negative ions
3

The conductivity of metals is high due to:

Metals have very low resistivity (\( 10^{-2} \) to \( 10^{-8} \, \Omega \, \text{m} \)) or high conductivity (\( 10^2 \) to \( 10^8 \, \text{S} \, \text{m}^{-1} \)) because of a large number of free electrons available for conduction.

Large number of free electrons
High energy gap
Covalent bonding
Presence of holes
1

In a half-wave rectifier, the output voltage appears across the load during:

A half-wave rectifier conducts only during the positive half-cycle of the AC input, allowing current through the load only in that period, producing a pulsating output for half the cycle.

Negative half-cycle
Full cycle
Zero voltage periods
Positive half-cycle
4

Which of the following materials has the highest resistivity?

Resistivity (\( \rho \)) distinguishes materials: metals have low resistivity (\( 10^{-2} \) to \( 10^{-8} \, \Omega \, \text{m} \)), semiconductors intermediate (\( 10^{-5} \) to \( 10^6 \, \Omega \, \text{m} \)), and insulators high (\( 10^{10} \) to \( 10^{19} \, \Omega \, \text{m} \)). Among the options, insulators have the highest resistivity.

Insulators
Metals
Semiconductors
Conductors
1

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