Q4. A two-lead component gives a low reading one way and a very high one the other, and does not glow. On the NCERT-type analog multimeter with black verified positive in resistance mode, the low reading came with the black lead on end A. Name the component and its p-side.
A diode, with its p-side at end A: the black lead is the positive one in resistance mode, so the diode conducted when A was positive (Laboratory Manual, page 175).
Q5. Assertion: two different ohmmeters can give different forward resistances for the same good diode. Reason: a diode is not ohmic, and each meter sends a different current through it. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion (NEETS Module 7, page 1-33).
Q6. A resistor is banded brown, black, orange and silver. What are its resistance and the range allowed by its tolerance?
Brown 1, black 0, orange the multiplier 103: R = 10 × 103 = 10 kΩ. Silver means ±10%, so 9 kΩ to 11 kΩ (Laboratory Manual, page 172).
Q7. A diode gives a low reading with the leads either way round. What is wrong with it?
It is shorted, or has a low reverse resistance (NEETS Module 7, page 1-32).
Q8. An LED glows when the multimeter’s leads are on its two legs. On the NCERT-type analog meter with black verified positive in resistance mode, which lead is on the longer leg?
The black lead. The LED glows only when forward biased, with its p-side, usually the longer leg, positive, and the black lead is the positive one in resistance mode (Laboratory Manual, pages 173 and 175).
Q9. With the meter’s internal resistance taken as 20 kΩ, how large a capacitance gives a charging kick with a time constant of 2 s?
C = τ/R = 2/(20 × 103) = 1.0 × 10−4 F, that is 100 μF (reasoned, τ = RC).