Semiconductor and Transistor Quiz

A semiconductor is formed by ........ bonds.

• covalent

• electrovalent

• co-ordinate

• none of the above

A semiconductor has ........ temperature coefficient of resistance.

• positive

• zero

• negative

• none of the above

The most commonly used semiconductor is ........

• germanium

• silicon

• carbon

• sulphur

Addition of pentavalent impurity to a semiconductor creates many ........

• free electrons

• holes

• valence electrons

• bound electrons

The barrier voltage at a pn junction for germanium is about ........

• 3.5 V

• 3V

• zero

• 0.3 V

A crystal diode has ........

• one pn junction

• two pn junctions

• three pn junctions

• none of the above

If the arrow of crystal diode symbol is positive w.r.t. bar, then diode is ........ biased.

• forward

• reverse

• either forward or reverse

• none of the above

Zener diodes are used primarily as

• amplifiers

• voltage regulators

• rectifiers

• oscillators

A pn junction that radiates energy as light instead of as heat is called a

• LED

• photo-diode

• photocell

• Zener diode

A photo-diode is normally

• forward-biased

• reverse-biased

• Neither forward nor reverse biased

• Emitting light