Electronics Questions to MCQs

Which of the following elements is most frequently used for doping pure Ge or Si?

• a. Boron

• b. Gallium

• c. Indium

• d. All of the above

Assume the valence electrons is removed from a copper atom. The net charge of the atom becomes:

• a. 0

• b. +1

• c. -1

• d. +4

Suppose there is an atom of oxygen, containing eight protons and eight neutrons in the nucleus, and four neutrons are added in the nucleus. The resulting atomic weight is about:

• a. 16

• b. 18

• c. 20

• d. 24

At absolute zero temperature an intrinsic semiconductor has:

• a. A few electrons

• b. Many holes

• c. Many free electrons

• d. no holes or free electrons

As the temperature of a semiconductor is reduced below normal room temperature, the resistivity increases until, at very low temperatures the semiconductor becomes:

• a. a conductor

• b. an insulator

• c. saturated

• d. defective

An intrinsic semiconductor has some holes in it at room temperature, What causes these holes?

• a. Doping

• b. Free electrons

• c. Thermal energy

• d. Valence electrons

Each atom in a silicon crystal has

• a. four valence electrons

• b. four conduction electrons

• c. eight valence electrons, four of its own and four shared

• d. no valence electrons because all are shared with other atoms

As the forward current through a silicon diode increases, the voltage across the diode:

• a. increases to a 0.7 V maximum

• b. decreases

• c. is relatively constant

• d. decreases and then increases

A silicon diode has a saturation current of 5nA at 25 degrees C. What is the saturation current at 88 degrees C?

• a. 392 nA

• b. 370 nA

• c. 640 nA

• d. 650 nA

If a surface leakage current is 4nA for a reverse voltage of 35V, what is the surface leakage current for a reverse voltage of 43V?

• a. 2.8nA

• b. 3.3nA

• c. 4.9nA

• d. 8nA