Question

A wire of length L and mass per unit length 6.0 × 10^–3 kgm^–1 is put under tension of 540 N. Two consecutive frequencies that it resonates at are : 420 Hz and 490 Hz. Then L in meters is :

(1) 8.1 m

(2) 5.1 m

(3) 1.1 m

(4) 2.1 m 

Answer 1

The correct answer is (4) 2.1 m

Answer 2

Answer is (4) 2.1 m

Fundamental frequency = 490 – 420 = 70 Hz