The resonance length obatined by a student in determination of frequency by a student in determination of frequency of a.c. mains by sonometer is `26.7 cm`. If thickness of sonometer wire were doubled without changing any other parameter, the resonance length would be

Options

A. 26.7 cm
B. 53.4 cm
C. 13.4 cm
D. none of the above

Answer

C

Explanation

From `(1)/(lD) sqrt((T)/(pi d))`
As n is `l xx D =` constant. When D is double become half. Therefore, new resonance length `= (26.7)/(2) = 13.35 cm = 13.4 cm`