Question

Which of the following combinations should be selected for better tuning of an LCR circuit used for communication? [NCERT Exemplar]
(a) R = 20, L= 1.5 H, C = 35 μF.
(b) R = 25 , L = 2.5 H, C = 45 μF.
(c) R = 15 , L = 3.5 H, C = 30 μF.
(d) R = 25 , L = 1.5 H, C = 45 μF.

Answer 1

Answer:

GIVEN =  (a) R = 20, L= 1.5 H, C = 35 μF.

               (b) R = 25 , L = 2.5 H, C = 45 μF.

               (c) R = 15 , L = 3.5 H, C = 30 μF.

               (d) R = 25 , L = 1.5 H, C = 45 μF.

to find = suitable combination for better  tuning  an LCR.

solution,

for better tuning of an LCR circuit used for communication must be posesed high quality factor of resonnce.

so, Q = 1/R$\sqrt{} \frac{L}{C}$ ,

in option 3rd, the Q factor is highest.

Q = 1/15 $\sqrt{\frac{3.5}{30 x 10} }$

Q = 22.7

the value of Q in case of a , b and d can be 10.35,9.42 and 7.30 respectively.

the highest value of Q is present in OPTION C so option C is the correct answer.