Electronics Information Test Flashcards

What is the unit of electrical capacitance?

Answer: Farad

Capacitance is measured in farads (F), named after Michael Faraday.

In a parallel circuit with three 6-ohm resistors, what is the total resistance?

Answer: 2 ohms

In parallel, total resistance = 1/(1/6+1/6+1/6) = 6/3 = 2 ohms.

What does a diode primarily do in a circuit?

Answer: Allows current to flow in only one direction

A diode is a semiconductor device that permits current to flow in one direction only.

Which type of transformer steps voltage up from primary to secondary coil?

Answer: Step-up transformer

A step-up transformer has more turns on the secondary coil than the primary, increasing voltage.

What is the color code for a resistor with bands: Red, Red, Brown, Gold?

Answer: 220 ohms ±5%

Red=2, Red=2, Brown=×10 multiplier, Gold=±5% tolerance gives 220 ohms ±5%.

What happens to capacitive reactance as frequency increases?

Answer: It decreases

Capacitive reactance Xc = 1/(2πfC), so it decreases as frequency increases.

Which semiconductor device can function as both a switch and an amplifier?

Answer: Transistor

A transistor can amplify signals or act as an electronic switch depending on how it is biased.

What is the primary purpose of a fuse in an electrical circuit?

Answer: Protect against overcurrent

A fuse melts and opens the circuit when current exceeds a safe level, protecting components.

If a circuit has 12V across a 4-ohm resistor, how much power is dissipated?

Answer: 36 watts

P = V²/R = 12²/4 = 144/4 = 36 watts.

What does the term 'frequency' refer to in AC circuits?

Answer: The number of complete cycles per second

Frequency is measured in hertz (Hz) and indicates how many complete cycles occur each second.

What type of circuit has only one path for current to flow?

Answer: Series circuit

In a series circuit, all components share the same single current path.

What is the function of an inductor in an AC circuit?

Answer: Opposes changes in current

An inductor opposes changes in current due to its self-induced back-EMF (inductive reactance).

Which material is considered a semiconductor?

Answer: Silicon

Silicon is a classic semiconductor used in transistors, diodes, and integrated circuits.

In electrical wiring, what does AWG stand for?

Answer: American Wire Gauge

AWG stands for American Wire Gauge, a standardized system for wire diameter sizes.

What is the relationship between inductive reactance and frequency?

Answer: Directly proportional

Inductive reactance XL = 2πfL, so it increases proportionally as frequency increases.

What is the function of a rectifier in a power supply?

Answer: Converts AC to DC

A rectifier uses diodes to convert alternating current (AC) into direct current (DC).

When two capacitors are connected in series, the total capacitance is:

Answer: Less than the smallest capacitor

Series capacitors combine like parallel resistors: 1/Ct = 1/C1 + 1/C2, yielding a smaller total.

What is the purpose of a voltage regulator IC in a circuit?

Answer: Maintain a stable output voltage despite input variations

A voltage regulator IC keeps the output voltage constant regardless of load or input fluctuations.

What type of logic gate outputs HIGH only when all inputs are HIGH?

Answer: AND gate

An AND gate produces a HIGH output only when every input is HIGH; otherwise, output is LOW.

A circuit draws 3 amperes from a 9-volt battery. What is the circuit's resistance?

Answer: 3 ohms

Using Ohm's Law: R = V/I = 9/3 = 3 ohms.