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Question
Three students, X, Y and Z performed an experiment for studying the variation of a.c. with frequency in a series LCR circuit and obtained the graphs as shown below. They all used
- an AC source of the same emf and
- inductance of the same value.
- Who used minimum resistance?
- In which case will the quality Q factor be maximum?
- What did the students conclude about the nature of impedance at resonant frequency (f0)?
- An ideal capacitor is connected across 220V, 50Hz, and 220V, 100Hz supplies. Find the ratio of current flowing through it in the two cases.
Solution
- Resistance used by X is the least and resistance used by Z is the maximum.
- Q maximum for X
- At resonance impedance is equal to ohmic resistance.
- In a capacitor the current is dependent directly on frequency `"I"_1/"I"_2 = 1/2`
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