NEET Electronic Devices — Set 6

Question 1

A Si crystal with $ 5 \times 10^{28} \, \text{atoms} \, \text{m}^{-3} $ is doped with 0.5 ppm of pentavalent impurity. The number of donor electrons per cubic meter is:

Accepted Answer

0.5 ppm = $ 0.5 \times 10^{-6} $. Number of donor atoms = $ 0.5 \times 10^{-6} \times 5 \times 10^{28} = 2.5 \times 10^{22} \, \text{m}^{-3} $, each contributing one electron.

Question 2

The space-charge region in a p-n junction is also known as:

Accepted Answer

The space-charge region, formed by immobile ionized impurities after carrier diffusion, is called the depletion region due to the absence of free charge carriers.

Question 3

The forward bias current in a diode is typically measured in:

Accepted Answer

In forward bias, the current due to majority carrier diffusion is large, typically in the milliampere (mA) range, requiring a milliammeter for measurement.

NEET Physics: Electronic Devices — Practice Set 6

Q1. A Si crystal with \( 5 \times 10^{28} \, \text{atoms} \, \text{m}^{-3} \) is doped with 0.5 ppm of pentavalent impurity. The number of donor electrons per cubic meter is:

Q2. The space-charge region in a p-n junction is also known as:

Q3. The forward bias current in a diode is typically measured in:

Q4. The reverse bias resistance of a p-n junction diode is typically:

Q5. The voltage drop in a forward-biased diode occurs mainly across:

Q6. In an extrinsic semiconductor, the minority carrier concentration is reduced due to:

Q7. The majority carriers in a p-type semiconductor are:

Q8. Which of the following has the highest energy gap?

Q9. In a full-wave rectifier, the voltage across each diode is:

Q10. What is the primary source of charge carriers in an intrinsic semiconductor at room temperature?