Loudspeakers are driven with alternating current because DC currents produce no sound. Treat the

loudspeaker as a resistive load $($shown below$).$

a$.$ The humans can hear sounds in the frequency range from $20Hz$ to $20kHz.$ Determine if the tone $($frequency$)$ coming from the audio amplifier is audible. Explain your answer.

b$.$ The loudspeaker's magnetic coils will melt if they dissipate more than a quarter watt of average power. Show that the loudspeaker will not melt when operating as shown in the figure.