#1 Basic Electronics MCQ

---

Question 1 The most commonly used semiconductor is ………

• Germanium
• Silicon
• Carbon
• Sulphur

Answer – Silicon

Question 2 The resistivity of a pure silicon is about ……………

• 100 Ω cm
• 6000 Ω cm
• 3 x 105 Ω m
• 6 x 10-8 Ω cm

Answer – 6000 Ω cm

Question 3 A semiconductor is formed by ……… bonds.

• Covalent
• Electrovalent
• Co-ordinate
• None of the above

Answer – Covalent

Question 4 A pentavalent impurity has ………. Valence electrons

• 3
• 5
• 4
• 6

Answer – 5

Question 5 A semiconductor has generally ……………… valence electrons.

• 2
• 3
• 6
• 4

Answer – 4

Question 6 A hole in a semiconductor is defined as …………….

• A free electron
• The incomplete part of an electron pair bond
• A free proton
• A free neutron

Answer – The incomplete part of an electron pair bond

Question 7 Addition of trivalent impurity to a semiconductor creates many ……..

• Holes
• Free electrons
• Valence electrons
• Bound electrons

Answer – Holes

Question 8 Addition of pentavalent impurity to a semiconductor creates many ……..

• Free electrons
• Holes
• Valence electrons
• Bound electrons

Answer – Free electrons

Question 9 In a semiconductor, current conduction is due to …

• Only holes
• Only free electrons
• Holes and free electrons
• None of the above

Answer – Holes and free electrons

Question 10 The battery connections required to forward bias a pn junction are ……

• +ve terminal to p and –ve terminal to n
• -ve terminal to p and +ve terminal to n
• -ve terminal to p and –ve terminal to n
• None of the above

Answer – +ve terminal to p and –ve terminal to n

Question 11 A forward biased pn junction diode has a resistance of the order of

• Ω
• kΩ
• MΩ
• None of the above

Answer – Ω

Question 12 The barrier voltage at a pn junction for germanium is about ………

• 5 V
• 3 V
• Zero
• 0.3 V

Answer – 0.3 V

Question 13 A reverse bias pn junction has …………

• Very narrow depletion layer
• Almost no current
• Very low resistance
• Large current flow

Answer – Almost no current

Question 14 A pn junction acts as a ……….

• Controlled switch
• Bidirectional switch
• Unidirectional switch
• None of the above

Answer – Unidirectional switch

Question 15 In the depletion region of a pn junction, there is a shortage of ……..

• Acceptor ions
• Holes and electrons
• Donor ions
• None of the above

Answer – Holes and electrons

Question 16 The leakage current across a pn junction is due to …

• Minority carriers
• Majority carriers
• Junction capacitance
• None of the above

Answer – Minority carriers

Question 17 When the temperature of an extrinsic semiconductor is increased, the pronounced effect is on……

• Junction capacitance
• Minority carriers
• Majority carriers
• None of the above

Answer – Minority carriers

Question 18 With forward bias to a pn junction , the width of depletion layer ………

• Decreases
• Increases
• Remains the same
• None of the above

Answer – Decreases

Question 19 At room temperature, an intrinsic semiconductor has ……….

• Many holes only
• A few free electrons and holes
• Many free electrons only
• No holes or free electron

Answer – A few free electrons and holes

Question 20 The leakage current in a pn junction is of the order of

• Aa
• mA
• kA
• µA

Answer – µA

---

Topics

---

FAQ – Frequently ask questions