Technician License Course Chapter 3 Electricity, Components and Circuits Lesson Plan Module 5 Presented by: The Brookhaven National Laboratory Amateur Radio Club Instructor: Gary Stevens (KD5SFQ)

Fundamentals of Electricity When dealing with electricity, what we are referring to is the flow of electrons through a conductor. Electrons are negatively charged atomic particles. The opposite charge is the positive charge A conductor is a material that allows electrons to move with relative freedom within the material. You need to take some time to make sure all the students are on the same page when dealing with electronics fundamentals. You will probably find a wide range of knowledge from those who have no clue what you’re talking about to those who know far more about the topic than you do. Acknowledge this right up front, but tell the students you are going to lay the vocabulary foundation for material that follows. For those with little knowledge, tell them to hang on because it will become clear as the lesson proceeds. For those more knowledgeable, tell them to be patient and allow for a little instructor license to over simplify so that all can understand.

Fundamentals of Electricity In electronics and radio, we control the flow of electrons to make things happen. You need to have a basic understanding of how and why we control the flow of electrons so that you can better operate your radio. Use this time to provide some motivation of “why do I need to know this stuff.”

Basic Characteristics of Electricity There are three characteristics of electricity: Voltage Current Resistance All three must be present for electrons to flow.

Basic Characteristics of Electricity The flow of water through a hose is a good analogy to understand the three characteristics of electricity and how they are related. Take some time to talk the students through the water analogy. Pressure that pushes water through a hose, in electricity it is voltage (or Electromotive force). The water in the hose, in electricity it is the electrons (current) that will move. The friction that prevents the water from just freely moving through the hose, in electricity it is resistance. Resistance comes from the electrons running into obstacles within the conductor (and other electrons) as they pass through. Have the students rub their hands together and observe what happens (heat). When resistance impedes the flow of electronics (slows the flow down), the change in kinetic energy (energy of movement) must be turned into some form of energy (remember energy is neither created or destroyed), it is just turned into something else) in this case heat.

Characteristics of Electricity are Inter-related Voltage, current and resistance must be present to have current flow. Just like water flowing through a hose, changes in voltage, current and resistance affect each other. That effect is mathematically expressed in Ohm’s Law. If there is no push (voltage) there is no current (current by definition is flowing electrons), if there is no movement, there can be no resistance. If there is nothing to push, there will be no pressure, no movement - no resistance. There is always going to be some form of impediment to movement. What you are describing here is that inter-relationship which is Ohm’s law

The Electric Circuit: An Electronic Roadmap For current to flow, there must be a path from one side of the source of the current to the other side of the source – this path is called a circuit. There must be a hose (conductive path) through which the water (current) can flow. The following are some vocabulary words that help describe an electronic circuit. This would be a good time to illustrate a simple circuit diagram.

Series Circuits Series circuits provide one and only one path for current flow. Trace the flow of current through the circuit and show there is only one way for current to flow.

Parallel Circuits Parallel circuits provide alternative paths for current flow. Trace the current flow through the circuit and show that there are multiple paths for current flow.

Ohm’s Law E is voltage I is current R is resistance R = E/I I = E/R Units - volts I is current Units - amperes R is resistance Units - ohms R = E/I I = E/R E = I x R Go over the simple Ohm’s Law math and provide a few examples of how to solve problems. Give some homework problems that are the same as test questions (without telling them that they are test questions). Have the students solve these problems so they are confident that they can do the math.

Moving Electrons Doing Something Useful Any time energy is expended to do something, work is performed. When moving electrons do some work, power is consumed. Power is measured in the units of watts (W). Discuss the concept of power in electronics. Student will probably be familiar with this concept because of their electric bill.

Power Formula Power is defined as the amount of current that is being pushed through a conductor or device to do work. P = E x I E = P/I I = P/E Go through some simple problems using the power formula. Again use test question examples for homework. PP P I E

Two Basic Kinds of Current When current flows in only one direction, it is called direct current (dc). Batteries are a common source of dc. Most electronic devices are powered by dc. When current flows alternatively in one direction then in the opposite direction, it is called alternating current (ac). Your household current is ac. Discuss the two different kinds of current and what they might be used for. Point out to the students that their household ac current is frequently converted into dc to run many household appliances. That conversion is done inside the appliance or inside an external converter like a wall transformer. Explain why house current is ac (easier to transmit the electricity from the power plant to the home).

Digital Multi-Meter

What term describes the number of times per second that an alternating current reverses direction? (T3B02) A. Pulse rate B. Speed C. Wavelength D. Frequency

What term describes the number of times per second that an alternating current reverses direction? (T3B02) A. Pulse rate B. Speed C. Wavelength D. Frequency

Electrical current is measured in which of the following units? (T5A01) A. Volts B. Watts C. Ohms D. Amperes

Electrical current is measured in which of the following units? (T5A01) A. Volts B. Watts C. Ohms D. Amperes

Electrical power is measured in which of the following units? (T5A02) A. Volts B. Watts C. Ohms D. Amperes

Electrical power is measured in which of the following units? (T5A02) A. Volts B. Watts C. Ohms D. Amperes

What is the name for the flow of electrons in an electric circuit What is the name for the flow of electrons in an electric circuit? (T5A03) A. Voltage B. Resistance C. Capacitance D. Current

What is the name for the flow of electrons in an electric circuit What is the name for the flow of electrons in an electric circuit? (T5A03) A. Voltage B. Resistance C. Capacitance D. Current

What is the name for a current that flows only in one direction What is the name for a current that flows only in one direction? (T5A04) A. Alternating current B. Direct current C. Normal current D. Smooth current

What is the name for a current that flows only in one direction What is the name for a current that flows only in one direction? (T5A04) A. Alternating current B. Direct current C. Normal current D. Smooth current

What is the electrical term for an electromotive force (EMF) that causes electron flow? (T5A05) A. Voltage B. Ampere-hours C. Capacitance D. Inductance

What is the electrical term for an electromotive force (EMF) that causes electron flow? (T5A05) A. Voltage B. Ampere-hours C. Capacitance D. Inductance

Which of the following is a good electrical conductor? (T5A07) A. Glass B. Wood C. Copper D. Rubber

Which of the following is a good electrical conductor? (T5A07) A. Glass B. Wood C. Copper D. Rubber

Which of the following is a good electrical insulator? (T5A08) A. Copper B. Glass C. Aluminum D. Mercury

Which of the following is a good electrical insulator? (T5A08) A. Copper B. Glass C. Aluminum D. Mercury

What is the name for a current that reverses direction on a regular basis? (T5A09) A. Alternating current B. Direct current C. Circular current D. Vertical current

What is the name for a current that reverses direction on a regular basis? (T5A09) A. Alternating current B. Direct current C. Circular current D. Vertical current

Which term describes the rate at which electrical energy is used Which term describes the rate at which electrical energy is used? (T5A10) A. Resistance B. Current C. Power D. Voltage

Which term describes the rate at which electrical energy is used Which term describes the rate at which electrical energy is used? (T5A10) A. Resistance B. Current C. Power D. Voltage

What is the basic unit of electromotive force? (T5A11) A. The volt B. The watt C. The ampere D. The ohm

What is the basic unit of electromotive force? (T5A11) A. The volt B. The watt C. The ampere D. The ohm

What is the formula used to calculate electrical power in a DC circuit What is the formula used to calculate electrical power in a DC circuit? (T5C08) A. Power (P) equals voltage (E) multiplied by current (I) B. Power (P) equals voltage (E) divided by current (I) C. Power (P) equals voltage (E) minus current (I) D. Power (P) equals voltage (E) plus current (I)

What is the formula used to calculate electrical power in a DC circuit What is the formula used to calculate electrical power in a DC circuit? (T5C08) A. Power (P) equals voltage (E) multiplied by current (I) B. Power (P) equals voltage (E) divided by current (I) C. Power (P) equals voltage (E) minus current (I) D. Power (P) equals voltage (E) plus current (I)

What formula is used to calculate current in a circuit? (T5D01) A. Current (I) equals voltage (E) multiplied by resistance (R) B. Current (I) equals voltage (E) divided by resistance (R) C. Current (I) equals voltage (E) added to resistance (R) D. Current (I) equals voltage (E) minus resistance (R)

What formula is used to calculate current in a circuit? (T5D01) A. Current (I) equals voltage (E) multiplied by resistance (R) B. Current (I) equals voltage (E) divided by resistance (R) C. Current (I) equals voltage (E) added to resistance (R) D. Current (I) equals voltage (E) minus resistance (R)

What formula is used to calculate voltage in a circuit? (T5D02) A. Voltage (E) equals current (I) multiplied by resistance (R) B. Voltage (E) equals current (I) divided by resistance (R) C. Voltage (E) equals current (I) added to resistance (R) D. Voltage (E) equals current (I) minus resistance (R)

What formula is used to calculate voltage in a circuit? (T5D02) A. Voltage (E) equals current (I) multiplied by resistance (R) B. Voltage (E) equals current (I) divided by resistance (R) C. Voltage (E) equals current (I) added to resistance (R) D. Voltage (E) equals current (I) minus resistance (R)

What formula is used to calculate resistance in a circuit? (T5D03) A. Resistance (R) equals voltage (E) multiplied by current (I) B. Resistance (R) equals voltage (E) divided by current (I) C. Resistance (R) equals voltage (E) added to current (I) D. Resistance (R) equals voltage (E) minus current (I)

What formula is used to calculate resistance in a circuit? (T5D03) A. Resistance (R) equals voltage (E) multiplied by current (I) B. Resistance (R) equals voltage (E) divided by current (I) C. Resistance (R) equals voltage (E) added to current (I) D. Resistance (R) equals voltage (E) minus current (I)

Which instrument would you use to measure electric potential or electromotive force? (T7D01) A. An ammeter B. A voltmeter C. A wavemeter D. An ohmmeter

Which instrument would you use to measure electric potential or electromotive force? (T7D01) A. An ammeter B. A voltmeter C. A wavemeter D. An ohmmeter

What is the correct way to connect a voltmeter to a circuit? (T7D02) A. In series with the circuit B. In parallel with the circuit C. In quadrature with the circuit D. In phase with the circuit

What is the correct way to connect a voltmeter to a circuit? (T7D02) A. In series with the circuit B. In parallel with the circuit C. In quadrature with the circuit D. In phase with the circuit

How is an ammeter usually connected to a circuit? (T7D03) A. In series with the circuit B. In parallel with the circuit C. In quadrature with the circuit D. In phase with the circuit

How is an ammeter usually connected to a circuit? (T7D03) A. In series with the circuit B. In parallel with the circuit C. In quadrature with the circuit D. In phase with the circuit

Which instrument is used to measure electric current? (T7D04) A. An ohmmeter B. A wavemeter C. A voltmeter D. An ammeter

Which instrument is used to measure electric current? (T7D04) A. An ohmmeter B. A wavemeter C. A voltmeter D. An ammeter

What instrument is used to measure resistance? (T7D05) A. An oscilloscope B. A spectrum analyzer C. A noise bridge D. An ohmmeter

What instrument is used to measure resistance? (T7D05) A. An oscilloscope B. A spectrum analyzer C. A noise bridge D. An ohmmeter

Which of the following might damage a multimeter? (T7D06) A. Measuring a voltage too small for the chosen scale B. Leaving the meter in the milliamps position overnight C. Attempting to measure voltage when using the resistance setting D. Not allowing it to warm up properly

Which of the following might damage a multimeter? (T7D06) A. Measuring a voltage too small for the chosen scale B. Leaving the meter in the milliamps position overnight C. Attempting to measure voltage when using the resistance setting D. Not allowing it to warm up properly

Which of the following measurements are commonly made using a multimeter? (T7D07) A. SWR and RF power B. Signal strength and noise C. Impedance and reactance D. Voltage and resistance

Which of the following measurements are commonly made using a multimeter? (T7D07) A. SWR and RF power B. Signal strength and noise C. Impedance and reactance D. Voltage and resistance

What is probably happening when an ohmmeter, connected across a circuit, initially indicates a low resistance and then shows increasing resistance with time? (T7D10) A. The ohmmeter is defective B. The circuit contains a large capacitor C. The circuit contains a large inductor D. The circuit is a relaxation oscillator

What is probably happening when an ohmmeter, connected across a circuit, initially indicates a low resistance and then shows increasing resistance with time? (T7D10) A. The ohmmeter is defective B. The circuit contains a large capacitor C. The circuit contains a large inductor D. The circuit is a relaxation oscillator

Which of the following precautions should be taken when measuring circuit resistance with an ohmmeter? (T7D11) A. Ensure that the applied voltages are correct B. Ensure that the circuit is not powered C. Ensure that the circuit is grounded D. Ensure that the circuit is operating at the correct frequency

Which of the following precautions should be taken when measuring circuit resistance with an ohmmeter? (T7D11) A. Ensure that the applied voltages are correct B. Ensure that the circuit is not powered C. Ensure that the circuit is grounded D. Ensure that the circuit is operating at the correct frequency