If the frequency of a wave is increased by 25 %, then the change in it

1.	If the frequency of a wave is increased by 25 %, then the change in its wavelength will be:(medium not changed)(A) 20% increase17.(B)20% decrease(C) 25% increase(D) 25% decrease
Answer» wavelength = v/f now when f is increased by 1.25f => now, wavelength = v/1.25f = 100v/125f = 4v/5f so, new wavelength = 4/5(old wavelength) => % decrement = (1-4/5)100% = 100/5 = 20%

If the frequency of a wave is increased by 25 %, then the change in its wavelength will be:(medium not changed)(A) 20% increase17.(B)20% decrease(C) 25% increase(D) 25% decrease

Answer»

wavelength = v/f

now when f is increased by 1.25f

=> now, wavelength = v/1.25f = 100v/125f = 4v/5f

so, new wavelength = 4/5*(old wavelength) => % decrement = (1-4/5)*100% = 100/5 = 20%