Wave Motion 2 Question 33

33. A wave disturbance in a medium is described by y(x,t)=0.02cos(50πt+π2)cos(10πx), where x and y are in metre and t is in second.

(1995,2M)

(a) A node occurs at x=0.15m

(b) An antinode occurs at x=0.3m

(c) The speed of wave is 5ms1

(d) The wavelength of wave is 0.2m

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Answer:

Correct Answer: 33. (a, b, c, d)

Solution:

  1. It is given that y(x,t)=0.02cos(50πt+π/2)cos(10πx)

Acos(ωt+π/2)coskx

Node occurs when kx=π2,3π2 etc.

10πx=π2,3π2x=0.05m,0.15m

option (a)

Antinode occurs when kx=π,2π,3π etc.

10πx=π,2π,3π etc. x=0.1m,0.2m,0.3m option (b) 

Speed of the wave is given by,

v=ωk=50π10π=5m/s

option (c)

Wavelength is given by,

λ=2πk=2π10π=(15)m=0.2m

option (d)



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