Question

At resonance, the amplitude of forced oscillations is
A) Minimum
B) Maximum
C) Zero
D) None of these.

Answer 1

Hint: Have you ever noticed how we are able to use radio. Actually the waves oscillate and push the next immediate wave with more energy and hence we get our song. Unless there is any damping, at resonance whenever there is a forced oscillation the amplitude increases because of the factor of pushing one to another in a forced way.

Complete step by step solution:
Forced oscillations occur when an oscillating system is driven by a periodic force that is external to the oscillating system. The physically interesting aspect of a forced oscillator is its response—how much it moves to the imposed driving force.
Definition of resonance: Phenomenon in which an external force or a vibrating system forces another system around it to vibrate with greater amplitude at a specified frequency of operation.
Resonance is identified by a maximum in amplitude. The driving force is then always adding energy to the system, which will increase indefinitely unless there is some form of damping (e.g., friction) which removes energy from the system at a faster rate as amplitude increases

$\therefore$ At resonance, the amplitude of forced oscillations is Maximum. Hence, option (B) is correct.

Additional information:
Application of resonance:
(i) Swing. A playground swing is one of the familiar examples of resonance
(ii) Guitar. A guitar produces sound entirely by vibration
(iii) Pendulum
(iv) Singer Breaking a Wine Glass
(v) Bridge.
(vi) Music system playing on the high heavy beat.
(vii) Singing in the shower.
(viii) Radio.
A very important point to note is that the system oscillates with the driven frequency and not its natural frequency in Forced Simple Harmonic Motion. If it oscillates with its natural frequency, the motion will die out. A good example of forced oscillations is when a child uses his feet to move the swing or when someone else pushes the swing to maintain the oscillations.

Note:
Damping plays a role whenever there is a wave travelling from one place to another. Damping means obstruction in the path. When a wave travels we can say that if there is no damping then the wave travel with no or less energy loss and the opposite will happen if damping occurs.