Resonance can be looked at as forced vibration with the
a) least amount of energy input. b) maximum amount of energy input. c) matching of wave amplitudes. d) matching of constructive and destructive interference. e) minimum beat frequency.

B) Maximum amount of energy input.

Explanation:

Resonance is caused when a periodic motion is supported by an external periodic force. In resonance, frequency of periodic motion and frequency of  external periodic motion becomes equal. In this case there is maximum absorption of energy by the system. Take the case of a boy who is enjoying a ride on a swing which is supported by an external  periodic pushing from behind, resulting in swing  motion with maximum amplitude. .

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it