posted by Satej .
Resonance in a system, such as a string fixed at both ends, occurs when
a) it is oscillating in simpler harmonic motion
b) its frequency is the same as the frequency of an external source
c) its frequency is greater than the frequency of an external source
d) its frequency is smaller that the frequency of an external source
well, I don't like b,c,d. I would have worded it as "natural frequency" is ...
Assuming the author meant that, then b makes perfect sense.
Am I nitpicking? No. The frequency observed will always be the same as the external source. Duh. Resonance is when the external source is tuned to the natural frequency of the object.