Explain briefly why a capacitor can block DC voltage. How might you use this feature in a design? Explain why the impedance Zeq of a parallel RC circuit decreases as the frequency increases.
Discuss why the primary of a power transformer would have excessive current if the secondary were short-circuited. Why would there be no voltage across the secondary if the primary is open? Explain how a transformer with a 1:1 turns ratio and isolated secondary can be used to reduce the chance of electric shock from a 120-Vac power line.