Q122 / 150 · MHT CET 2019 (Shift 2) · Physics

A stretched wire of length 260 cm is set into vibrations. It is divided into three segments whose frequencies are in the ratio 2:3:4 . Their lengths must be

  • A
    80 cm, 60 cm, 120 cm
  • Correct answer
    B
    120 cm, 80 cm, 60 cm
  • C
    60 cm, 80 cm, 120 cm
  • D
    120 cm, 60 cm, 80 cm

Solution

The frequency produced by a stretched wire is given by
f=p2lTm … (i)
Where, p = number of loops formed in vibration,
l = length of wire,
T = tension in wire,
and m = mass per unit length of wire
So, form Eq (i), we get
f∝1l
Here, the ratio of frequencies of three segments is
f1:f2:f3=2:3:4
⇒l1:l2:l3=12:13:14
=6:4:3
The length of wire, L = 260 cm, so
l1=613×260=120 cm
l2=413×260=80 cm
andl3=313×260=60 cm

Hence, the correct answer is option: 'B'.

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