Two Identical Tuning Forks Vibrate at 256 Hz

Multiple Choice

Two identical tuning forks vibrate at 256 Hz. One of them is then loaded with a drop of wax, after which 6 beats per second are heard. The period of the loaded tuning fork is:

A) 0.006 s
B) 0.005 s
C) 0.004 s
D) 0.003 s
E) none of these