NEET Electronic Devices — Set 7

Question 1

In a full-wave rectifier, the number of diodes typically used with a centre-tap transformer is:

Accepted Answer

A full-wave rectifier with a centre-tap transformer uses two diodes, each conducting during alternate half-cycles, to rectify both positive and negative halves of the AC input.

Question 2

In an intrinsic semiconductor, the total current is the sum of:

Accepted Answer

The total current ($ I $) in an intrinsic semiconductor is the sum of electron current ($ I_e $) and hole current ($ I_h $), i.e., $ I = I_e + I_h $.

Question 3

In an n-type semiconductor, the donor impurities contribute:

Accepted Answer

Pentavalent donor impurities (e.g., As, P) in an n-type semiconductor donate extra electrons for conduction, significantly increasing the number of free electrons beyond intrinsic levels.

NEET Physics: Electronic Devices — Practice Set 7

Q1. In a full-wave rectifier, the number of diodes typically used with a centre-tap transformer is:

Q2. In an intrinsic semiconductor, the total current is the sum of:

Q3. In an n-type semiconductor, the donor impurities contribute:

Q4. The forward current in a p-n junction diode increases significantly beyond:

Q5. A pure Si crystal is doped with 1 ppm of pentavalent impurity. If the Si atom density is \( 5 \times 10^{28} \, \text{m}^{-3} \), the number of donor atoms per cubic meter is:

Q6. In a p-type semiconductor, the acceptor impurities create:

Q7. A silicon diode has a threshold voltage of approximately:

Q8. The resistivity of a semiconductor typically lies in the range:

Q9. In an intrinsic semiconductor, the hole movement is due to:

Q10. In forward bias, the effective barrier height of a p-n junction is:

Q11. In an intrinsic semiconductor, the number of free electrons (\( n_e \)) is equal to:

Q12. The maximum number of electrons that can occupy the outer orbit of a Si atom is:

Q13. Which material among Si, Ge, and Sn behaves as a metal?

Q14. In a reverse-biased p-n junction, the effective barrier height is: