Final answer:
Connecting a load to the second stage output of a transformer-coupled amplifier causes the output voltage to decrease, due to an increase in resistance and the constant power relationship within the transformer.
Step-by-step explanation:
When an external load is connected across the second stage output of a transformer-coupled amplifier, the output voltage decreases. This is because the transformer's voltage and current relationship follows Ohm's Law, where an increase in load (which means an increase in resistance) leads to a decrease in voltage.
The electrical power output of a transformer is designed to equal its input power, assuming negligible resistance. This is represented by the equation Pp = IpVp = IsVs = Ps, where power is the product of current (I) and voltage (V), with the subscripts 'p' representing 'primary' and 's' representing 'secondary.' Given that the power (P) should remain constant, if the output voltage (Vs) drops due to an increased load causing a higher current (Is), the transformer tries to conserve power but there could still be a decrease in voltage.