Which of the following combinations should be selected for better turning of an LCR circuit used for communication ?

Options

A. R = 20 `Omega` , L = 1.5h, C = `35mu`F
B. R = `25Omega` , L = 2.5 H , C = `45mu`F
C. R = `15Omega` , L = 3.5 H , C = `30mu`F
D. R = `25Omega`, L = 3.5 H, C = `45mu`F

Answer

C

Explanation

(c) Quality factor (Q) of an L-C-R circuit is given by,
`Q = 1/R sqrt (L/C)`
Where R is resistance, L is inductance and C is capacitance of
the circuit . To make Q high ,
R should be low, L should be high and C should be low .
these conditions are best satisfied by the values given in option (c)
Note : we shoiuld be careful while writing formula for quality factor, because we are considering series L-C-R circuit .