Electron Devices and Circuits Quiz 1

In the energy band structure, what distinguishes a conductor from an insulator?

• Conductors have no energy gap between valence and conduction bands

• Insulators have a large energy gap (> 5 eV) between valence and conduction bands

• Conductors have overlapping valence and conduction bands

• All of the above

The energy gap of silicon at room temperature is approximately:

• 0.7 eV

• 1.1 eV

• 1.4 eV

• 3.2 eV

In an intrinsic semiconductor at room temperature, the carrier concentration is:

• Equal number of electrons and holes

• More electrons than holes

• More holes than electrons

• Zero carriers

When a trivalent impurity is added to pure silicon, it creates:

• N-type semiconductor with excess electrons

• P-type semiconductor with excess holes

• Intrinsic semiconductor

• Insulator

The minority carrier concentration in an N-type semiconductor:

• Increases with temperature

• Decreases with temperature

• Remains constant

• Becomes zero

In a PN junction diode under forward bias:

• The depletion region width increases

• The barrier potential increases

• Current flows easily

• The junction acts as an open circuit

The knee voltage of a silicon diode is approximately:

• 0.3 V

• 0.7 V

• 1.1 V

• 1.4 V

In a half-wave rectifier, the efficiency is approximately:

• 40.6%

• 81.2%

• 66.7%

• 90%

The ripple factor of a full-wave center-tap rectifier is:

• 1.21

• 0.482

• 0.693

• 0.406

Which rectifier circuit provides the highest efficiency?

• Half-wave rectifier

• Full-wave center-tap rectifier

• Bridge rectifier

• All have same efficiency