JEE Main20198 Apr 2019Morning ShiftPhysicsWaves and SoundActual
A wire of length 2 L , is made by joining two wires A and B of same length but different radii r and 2 r and made of the same material. It is vibrating at a frequency such that the joint of the two wires forms a node. If the number of antinodes in wire A is p and that in B is q then ratio p : q is:
Options
- A3 : 5
- B4 : 9
- C1 : 4
- D1 : 2
Correct answer
D. 1 : 2
Step-by-step solution
For rod A, f 1 = n 1 2 l T ρ A 1 For rod B, f 2 = n 2 2 l T ρ A 2 Given f 1 = f 2 n 1 2 l T ρ A 1 = n 2 2 l T ρ A 2 n 1 2 l T ρ A 1 = n 2 2 l T ρ ( 4 A 1 ) ∵ r B = 2 r A A 2 = 4 A 1 n 1 = n 2 2 n 1 n 2 = 1 2