Electronics

Physics, SSC-Punjab Class 10. This chapter is split into 40 topics and has 977 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Analog circuits and signals 24 questions
2. Diode circuits: forward or reverse biased 24 questions
3. Bits, bytes and binary numbers 28 questions
4. Truth tables: output columns for different row orders 24 questions
5. N-type semiconductors 25 questions
6. ADC numericals: levels, samples and bits 28 questions
7. Brain teasers: building gates from other gates 24 questions
8. AND gate: symbol, equation and truth table 24 questions
9. Fire alarm system and its logic 25 questions
10. Doping, pentavalent and trivalent impurities 24 questions
11. Reverse bias and leakage current 24 questions
12. Logic gates in devices: definitions, uses and exercise items 24 questions
13. Identifying a gate from its truth table 24 questions
14. NOT gate (inverter) 24 questions
15. Semiconductor diode: symbol, anode and cathode 24 questions
16. Diode circuit numericals 27 questions
17. PN junction and the depletion region 24 questions
18. NOR gate: symbol, equation and truth table 23 questions
19. Gate output conditions: which input combination? 28 questions
20. Digital-to-analog converter and digital data 23 questions
21. Current-voltage characteristic of a diode 25 questions
22. OR gate: symbol, equation and truth table 25 questions
23. Uses and importance of diodes 22 questions
24. Choosing a logic gate for a control situation 23 questions
25. LED circuit components and I-V characteristic 23 questions
26. Gate outputs for successive inputs 24 questions
27. P-type semiconductors and holes 24 questions
28. Boolean logic: switches, lamp and binary states 25 questions
29. Gate networks and combinations of gates 20 questions
30. Light-emitting diode: principle of action 25 questions
31. LED colour, materials and uses 23 questions
32. N-type versus P-type semiconductors 24 questions
33. NAND gate: symbol, equation and truth table 24 questions
34. Identifying analog and digital devices 26 questions
35. LED circuit numericals: series resistor and current 27 questions
36. Digital circuits and signals 24 questions
37. Forward bias of a PN junction 23 questions
38. Analog-to-digital converter: sampling, quantization, encoding 26 questions
39. Burglar alarm using a NAND gate and an LDR 25 questions
40. Electronics and semiconductors 24 questions

Sample questions: Electronics

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. A germanium diode has its cathode at 5 V while its anode is at 0 V. How is the diode behaving?

• A. Reverse biased, so it conducts
• B. Reverse biased, so it does not conduct(correct answer)
• C. Forward biased, but it does not conduct
• D. Forward biased, so it conducts

Answer: B.The anode is at 0 V and the cathode at 5 V; the P-side is not at a higher potential, so the diode is reverse biased (or has no bias) and does not conduct.

Q2. With 2 V on the anode and 6 V on the cathode, in what state is a germanium diode?

• A. Forward biased, so it conducts
• B. Reverse biased, so it does not conduct(correct answer)
• C. Forward biased, but it does not conduct
• D. Reverse biased, so it conducts

Answer: B.The anode is at 2 V and the cathode at 6 V; the P-side is not at a higher potential, so the diode is reverse biased (or has no bias) and does not conduct.

Q3. Potentials of 1 V (anode) and 8 V (cathode) are applied to a germanium diode. What can be said about the diode?

• A. Reverse biased, so it does not conduct(correct answer)
• B. Forward biased, but it does not conduct
• C. Forward biased, so it conducts
• D. Reverse biased, so it conducts

Answer: A.The anode is at 1 V and the cathode at 8 V; the P-side is not at a higher potential, so the diode is reverse biased (or has no bias) and does not conduct.

Q4. With 4 V on the anode and 4.2 V on the cathode, in what state is a silicon diode?

• A. Forward biased, so it conducts
• B. Reverse biased, so it conducts
• C. Forward biased, but it does not conduct
• D. Reverse biased, so it does not conduct(correct answer)

Answer: D.The anode is at 4 V and the cathode at 4.2 V; the P-side is not at a higher potential, so the diode is reverse biased (or has no bias) and does not conduct.

Q5. Potentials of 0.5 V (anode) and 0 V (cathode) are applied to a silicon diode. What can be said about the diode?

• A. Forward biased, but it does not conduct(correct answer)
• B. Forward biased, so it conducts
• C. Reverse biased, so it conducts
• D. Reverse biased, so it does not conduct

Answer: A.The anode is 0.5 V above the cathode, which is below the 0.7 V threshold of a silicon diode, so it is forward biased but the current is negligible.

Q6. With 0 V on the anode and 0.5 V on the cathode, in what state is a germanium diode?

• A. Reverse biased, so it conducts
• B. Reverse biased, so it does not conduct(correct answer)
• C. Forward biased, so it conducts
• D. Forward biased, but it does not conduct

Answer: B.The anode is at 0 V and the cathode at 0.5 V; the P-side is not at a higher potential, so the diode is reverse biased (or has no bias) and does not conduct.

Q7. Potentials of 3 V (anode) and 12 V (cathode) are applied to a germanium diode. What can be said about the diode?

• A. Forward biased, but it does not conduct
• B. Reverse biased, so it conducts
• C. Reverse biased, so it does not conduct(correct answer)
• D. Forward biased, so it conducts

Answer: C.The anode is at 3 V and the cathode at 12 V; the P-side is not at a higher potential, so the diode is reverse biased (or has no bias) and does not conduct.

Q8. The Exercise asks why digital systems are more reliable than analog systems when signals travel long distances. A good answer is:

• A. digital signals are never affected by the cable at all, even if it is broken
• B. a small noise added on the way does not change a clear high or low(correct answer)
• C. digital signals need no wires to travel
• D. analog signals are always much stronger in a long cable

Answer: B.A digital receiver only needs to decide between two levels, so small distortion does not matter; an analog signal carries the distortion on.

Q9. Why would a security system use NAND gates instead of OR or AND gates for certain logical conditions?

• A. AND gates cannot be connected to a battery
• B. OR gates give no output when any input is high
• C. A NAND gate is the only gate that has two inputs
• D. Normal conditions(correct answer)

Answer: D.In a security circuit the inputs are normally 1 and the alarm must sound when any input falls to 0, which is exactly the NAND behaviour.

Q10. A fire alarm design drives the alarm output through an AND gate from the smoke and heat sensors, yet the alarm should sound when either smoke or heat is detected. Which gate would match this requirement?

• A. An OR gate(correct answer)
• B. A NOR gate with both inputs 1
• C. A NOT gate
• D. An AND gate

Answer: A.The text and the Brain Teaser describe OR logic for the alarm, so an AND gate for the alarm (as the book's circuit diagram labels it) is inconsistent with the text.