CBT - Certified Broadcast Technologist Electronic Fundamentals Questions and Answers — Questions and Answers
Question 1: A technician measures 120V across a circuit and 1.5A of current flowing through it. Using Ohm's Law, what is the resistance of the circuit?
- 180 Ohms
- 80 Ohms (Correct answer)
- 0.0125 Ohms
- 121.5 Ohms
Correct answer: 80 Ohms
Ohm's Law states that Resistance (R) is equal to Voltage (E) divided by Current (I), or R = E/I. In this scenario, R = 120V / 1.5A, which equals 80 Ohms.
Question 2: In a broadcast facility, three resistors with values of 100Ω, 200Ω, and 300Ω are connected in series. What is the total resistance of this combination?
- 54.5Ω
- 200Ω
- 600Ω (Correct answer)
- 1100Ω
Correct answer: 600Ω
When resistors are connected in series, the total resistance is the sum of the individual resistances. Therefore, RT = R1 + R2 + R3 = 100Ω + 200Ω + 300Ω = 600Ω.
Question 3: Which of the following electronic components is primarily used to amplify signals or act as an electronic switch?
- Capacitor
- Resistor
- Inductor
- Transistor (Correct answer)
Correct answer: Transistor
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is a fundamental building block of modern electronics used in applications like amplifiers and digital circuits.
Question 4: According to Kirchhoff's Current Law (KCL), what is the relationship of currents at a junction (or node) in a circuit?
- The total current entering a junction is greater than the total current leaving it.
- The algebraic sum of all voltages around a closed loop is zero.
- The total current leaving a junction is equal to the total current entering it. (Correct answer)
- The current is the same through all components in any circuit configuration.
Correct answer: The total current leaving a junction is equal to the total current entering it.
Kirchhoff's Current Law (KCL) is based on the conservation of charge and states that the algebraic sum of currents entering a junction must equal the algebraic sum of currents leaving that junction.
Question 5: A technician is working on an AC circuit for a transmitter and needs to calculate the capacitive reactance (Xc) of a 10µF capacitor at a frequency of 60Hz. What is the approximate capacitive reactance?
- 265 Ohms (Correct answer)
- 377 Ohms
- 1.67 Ohms
- 600 Ohms
Correct answer: 265 Ohms
The formula for capacitive reactance is Xc = 1 / (2Ï€fC). Plugging in the values: Xc = 1 / (2 * 3.14159 * 60Hz * 0.000010F), which calculates to approximately 265 Ohms.
Question 6: What is the primary function of a diode in an electronic circuit?
- To store electrical energy in a magnetic field.
- To resist the flow of current equally in both directions.
- To allow current to flow in only one direction. (Correct answer)
- To amplify the input signal.
Correct answer: To allow current to flow in only one direction.
A diode is a semiconductor device that acts as a one-way switch for current. It allows current to flow easily in one direction (forward bias) but severely restricts current from flowing in the opposite direction (reverse bias). This property is fundamental to processes like AC to DC rectification.
CBT - Certified Broadcast Technologist Electronic Fundamentals Questions and Answers
A technician measures 120V across a circuit and 1.5A of current flowing through it.
Using Ohm's Law, what is the resistance of the circuit?