A guitar is provided with tightening keys so that it can be tuned to a desired frequency by
changing its length
changing its thickness
changing its timbre
changing its tension
changing its radius
A tuning fork of frequency 256 Hz produces 4 beats per second with a wire of length 25 cm vibrating in its fundamental mode. The beat frequency decreases when the length is slightly shortened. What could be the minimum length by which the wire be shortened so that it produces no beats with the tuning fork ?