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Technician License Course Chapter 3 Electricity, Components and Circuits Lesson Plan Module 5

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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.

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Fundamentals of Electricity An insulator is a material that does not allow the free movement of electrons within the material. Common Conductors: Copper, Aluminum, Steel, Silver, Gold, Mercury Common Insulators: Glass, Rubber, Plastic, Bakelite

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Fundamentals of Electricit y 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.

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Basic Characteristics of Electricity There are three characteristics that exist in an electric circuit: –Voltage (electromotive force) –Current (electron flow rate) –Resistance (opposition to flow) All three must be present for electrons to flow.

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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.

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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.

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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.

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Series Circuits Series circuits provide one and only one path for current flow.

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Parallel Circuits Parallel circuits provide alternative paths for current flow.

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Ohm’s Law E is voltage –Units - volts I is current –Units - amperes R is resistance –Units - ohms R = E/I I = E/R E = I x R

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Ohm’s Law Practice

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Moving Electrons Doing Something Useful - POWER 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).

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Power Formula Power is defined as the amount of energy that is being used in a circuit or device to do work. –P = E x I –E = P/I –I = P/E –P = I 2 x R

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Electrical Terms –Voltage - (E) Electromotive Force measured in Volts (V) –Current - (I) Rate of Flow measured in Amperes (Amps) (A) –Resistance – (R) Opposition to Flow measured in Ohms ( ) –Power – (P) Rate of Energy Usage or Work Done measured in Watts (W)

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Electrical Measurements Measure electromotive force with a voltmeter, across (in parallel) with the circuit. Measure current with an ammeter, in series with the circuit. Measure resistance with an ohmmeter, with the power off. A multi-meter has all three meters in one package.

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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. –Power supplies can also supply dc. –Most electronic devices are powered by dc.

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Two Basic Kinds of Current When current flows alternatively in one direction then in the opposite direction, it is called alternating current (AC). –Your household current is ac. –60 Hz is the North American standard frequency –50 Hz is common in Europe –Radio Frequency (RF) energy is AC above 3kHz

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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

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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

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

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

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

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

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

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

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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

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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

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

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

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

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

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

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

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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

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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

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

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

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

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

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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)

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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)

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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)

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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)

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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)

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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)

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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)

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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)

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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

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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

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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

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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

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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

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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

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

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

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

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

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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

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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

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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

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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

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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

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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

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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

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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

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