In Figure, let the rectangular box on the left represent the (high-impedance) output of an audio amplifier, with r = 1000 . Let R =

In Figure, let the rectangular box on the left represent the (high-impedance) output of an audio amplifier, with r = 1000 Ω. Let R = 10 Ω represent the (low-impedance) coil of a loudspeaker. For maximum transfer of energy to the load R we must have R = r, and that is not true in this case. However, a transformer can be used to "transform" resistances, making them behave electrically as if they were larger or smaller than they actually are.

(a) Sketch the primary and secondary coils of a transformer that can be introduced between the amplifier and the speaker in Figure to match the impedances.

(b) What must be the turns ratio?

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