The loss-of-charge method is particularly suitable for measuring medium resistance values. Is this statement true or false?
Electronics and Communication Engineering
Measurements and Instrumentation
Difficulty: Easy
Choose an option
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ATrue
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BFalse
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CTrue only at low voltages
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DTrue only at high voltages
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EDepends on temperature
Answer
Correct Answer: True
Explanation
Introduction / Context:The loss-of-charge method is a classical technique for measuring medium resistance values using the discharge of a capacitor through the unknown resistance. It is commonly taught in electrical measurement courses.
Given Data / Assumptions:
- Principle: capacitor discharges through the resistance to be measured.
- Voltage across the capacitor decreases exponentially with time.
- By measuring time for a known voltage drop, resistance can be computed.
Concept / Approach:The method uses the relation V = V0 e^(-t/RC). Taking logs, R = t / (C ln(V0/V)). Accuracy depends on time measurement and insulation. Suitable resistances are typically 10^5 to 10^7 ohms (medium range).
Step-by-Step Solution:
Charge a capacitor to V0.Connect resistance under test.Measure time for voltage to fall to V.Use relation R = t / (C ln(V0/V)).Verification / Alternative check:
High resistances → leakage dominates; low resistances → discharge too fast; medium resistances ideal.Why Other Options Are Wrong:
”False” ignores well-established usage; voltage dependency is not the deciding factor; temperature only affects accuracy slightly.Common Pitfalls:
Trying to use this method for too high resistances where leakage interferes.Final Answer:
True