It is possible to hear beats from the two vibrating sources of frequency 

(1) 100 Hz and 150 Hz

(2) 20 Hz and 25 Hz

(3) 400 Hz and 500 Hz

(4) 1000 Hz and 1500 Hz

(2) For hearing beats, difference of frequencies should be approximately 10 Hz.

Difficulty Level:

  • 10%
  • 70%
  • 16%
  • 6%