AC Circuits

Both step-down and step-up voltage transformers keep power constant. A 5-volt source supplies 20 watts of power to an AC circuit. What is the power produced after the current passes through a voltage step-down transformer with a 1 to 5 ratio?

20 watts

The equations for capacitors in parallel and series circuits are the opposite of those for resistance. Capacitors in Parallel: CT= C1 + C2 + C3 + ... Capacitor in Series: CT= 11C1 + 1C2 + 1C3 + ... What is the capacitance of a circuit containing three parallel capacitors of 2 F, 1 F, and 1.5 F?

4.50 F

Direct Current (DC) is typically provided from a battery or from a rectified AC source. Alternating Current (AC) is supplied by a generator or by a DC source put through an inverter.

AC: Electron flow continuously changes value and periodically changes direction. ​

While resistors will oppose any current flow, inductors do not oppose current flow unless it is at least partly alternating current. Which component is a coil of wire that resists the flow of electrons in alternating current with a counter electromagnetic field?

An inductor

Transformers on AC devices manipulate electrical energy using induction. How can AC devices save weight on aircraft? Select two.

By manipulating voltage and current with transformers. AC motors are lighter than DC motors.

Ohm's Law for AC circuits involves impedance, Z. This is the total resistance to flow provided by the inductors and capacitors in an AC circuit. Which of the following describes Ohm's Law for AC circuits? Select three.

I=EZ, E= I×Z, Z=EI

It's important to understand how each of these components affects a circuit Match each term with its appropriate description.

Impedance- The combined opposition of current from all sources in an AC circuit. Inductor- A coil of wire that transfers electrical energy through a magnetic field. Resistor- An electrical component that resists the flow of electrons directly. Transformer- Multiple coils of wire wound around a core that manipulate voltage and current proportionally using induction. Capacitor- Stores electrical energy within metal plates separated by a small amount of insulating material.

Diodes are electronic components that allow electrons to pass freely in one direction but block their flow in the opposite direction. They are used as rectifiers in electrical circuits. How can an AC source be converted to DC?

Rectify the AC source with a diode.

Step-down transformers step down the voltage and increase the current. What happens to a current running through a voltage step-down transformer with a 3 to 1 ratio?

The current is stepped up by the same ratio.

Note that for DC, the graph is just a straight horizontal line. This graph is representative of a ___________.

generator.