Question

A wave equation is y=0.1sin[100πt-kx] and wave velocity is 100m/s, its number is equal to __________

(a) 1/m

(b) 2/m

(c) π/m

(d) 2π/m

I got this question by my college director while I was bunking the class.

Question is from Progressive Waves topic in chapter Waves of Engineering Physics I

Answer 1

Right option is (c) π/m

For explanation I would say: y=0.1sin⁡[100πt-kx]

y=Asin(ωt-kx)

ω=100π

Wave number=ω/v=100π/100=π/m.