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Technician Licensing Class These Power Point presentations are available to individuals who register with The W5YI Group’s HamInstructor.com program. The presentations are provided by Master Publishing and The W5YI Group and include material that is covered by U.S. and International copyrights. They are intended solely for the use of Registered Instructors using the Gordon West, WB6NOA, Technician Class, General Class, and Extra Class study manuals to teach FCC Amateur Radio Licensing Classes. Registration through HamInstructor.com constitutes a Licensing Agreement between The W5YI Group and the registered instructor under which the instructor agrees not to copy or distribute the Power Point presentations to unauthorized users. 1 Technician Licensing Class It’s the Law, per Mr. Ohm! Valid July 1, 2014 Through June 30, 2018 2 Amateur Radio Technician Class Element 2 Course Presentation ELEMENT 2 SUB-ELEMENTS (Groupings) • • • • • • • • • • About Ham Radio Call Signs Control Mind the Rules Tech Frequencies Your First Radio Going On The Air! Repeaters Emergency! Weak Signal Propagation 3 Amateur Radio Technician Class Element 2 Course Presentation ELEMENT 2 SUB-ELEMENTS (Groupings) • Talk to Outer Space! • Your Computer Goes Ham Digital! • Multi-Mode Radio Excitement • Run Some Interference Protection • Electrons – Go With the Flow! It’s the Law, per Mr. Ohm! • Picture This! • Antennas • Feed Me with Some Good Coax! • Safety First! 4 It’s the Law, per Mr. Ohm! 5 It’s the Law, per Mr. Ohm! • T5A10 Go outside your home or condo and gaze at the power meter measuring the rate at which electrical energy is being consumed by all the gadgets inside your new ham shack! Luckily, your modern ham gear won’t consume much energy so your power bill won’t go up by more than a few cents per month! That power meter on the side of your house is called a watt meter, and it is calculating your household voltage times the amount of amperes of current flowing to keep your radio station powered up! • T5A02 Power is energy, and power is measured in watts. 6 It’s the Law, per Mr. Ohm! • T5C08 Power in watts is equal to volts times current in amps. A 100-watt light bulb, running on 110 VAC house voltage, will draw about 1 amp. The magic circle for power is: P over E I. Cover the unknown quantity with your finger, and perform the mathematical operation represented by the remaining quantities. 7 It’s the Law, per Mr. Ohm! • T5C09 Power is equal to volts times amps. In this problem, multiple 13.8 volts by 10 amps, and you end up with 138 watts. This one you can do in your head. Easy as PIE! • T5C10 Power is equal to volts times amps. Multiple 12 volts by 2.5 amps, and you end up with 30 watts. 8 It’s the Law, per Mr. Ohm! • T5C11 This time we are calculating for amps, so it is power (120) divided by voltage (12). Do the keystrokes: Clear Clear 120 12 = 10. Again, just because they list power second in the question, it still goes on top at P, and they list voltage first in the question, and that goes on the bottom as E. I=PE I = 120 12 I = 10 Amperes 9 It’s the Law, per Mr. Ohm! • T5D02 Voltage = current x resistance, which is expressed as: E = I x R. This simple formula, called Ohm’s Law, states the relationship between voltage, current and resistance in an electrical circuit. 10 It’s the Law, per Mr. Ohm! • T5D10 Since we are looking for E in this question, the voltage across a resistor, cover E with your finger, and you now have I (0.5 amps) times R (2 ohms). Simply multiple these two values to obtain your answer of 1 volt. On your calculator, which is perfectly legal in the exam room, perform the following keystrokes: Clear Clear 0.5 X 2 = and the answer is 1 volt. Commit the magic circle of success to your memory now! E=IxR E = 0.5 x 2 E= 1 volt 11 It’s the Law, per Mr. Ohm! • T5D11 The question starts out, “What is the voltage across…” so put your finger across E and see that the current in this question is 1 amp through a 10 ohm resistor. One multiplied by 10 is… 10 volts. You can do this one in your head. E=IxR E = 1 x 10 E= 10 volts 12 It’s the Law, per Mr. Ohm! • T5D12 This question is looking for voltage, so we know it’s going to be a simple multiplication of 2 amperes through a 10-ohm resistor, with 20 volts as the correct answer. E=IxR E = 2 x 10 E= 20 volts 13 It’s the Law, per Mr. Ohm! • T5D01 For current, put your finger over I, and it is voltage (E) divided by resistance (R). I=ER 14 It’s the Law, per Mr. Ohm! • T5D09 Do the keystrokes: Clear Clear 240 24 = 10. Remember, to calculate current, it is voltage on top divided by resistance on the bottom. I=ER I = 240 24 I = 10 amperes 15 It’s the Law, per Mr. Ohm! • T5D08 Be careful on this question – they reversed the order of resistance and voltage that was in the previous question. In your magic circle, I = 200 100. Calculator keystrokes: Clear Clear 200 (volts on the top) 100 ohms (on the bottom) = 2 amperes. I=ER I = 200 100 I = 2 amperes 16 It’s the Law, per Mr. Ohm! • T5D07 Here they want to know current, so it is voltage (120 volts) divided by resistance (80 ohms). Here are your calculator keystrokes: Clear Clear 120 80 = 1.5. Be careful that you don’t reverse your division – they have an incorrect answer, C, just waiting for you! I = E R I = 120 80 I = 1.5 amperes 17 It’s the Law, per Mr. Ohm! • T5D03 Put your finger over resistance in the magic circle, and see that it is voltage divided by current. R=EI 18 It’s the Law, per Mr. Ohm! • T5D04 Be careful – they list current first which would go in the bottom of your magic circle, and voltage at the top. Keystrokes: Clear Clear 90 3 = 30. R=EI R = 90 3 R = 30 ohms 19 It’s the Law, per Mr. Ohm! • T5D05 In this problem, they list voltage first which is 12, on the top, divided by 1.5 amps on the bottom. Clear Clear 12 1.5 = 8. Read each question carefully because they switch around voltage and current, yet your magic circle always says to put voltage on the top and current on the bottom when solving for resistance. R=EI R = 12 1.5 R = 8 ohms 20 It’s the Law, per Mr. Ohm! • T5D06 Now remember, Gordo’s rule – on most Technician Class questions, you divide the larger number by the smaller number, and presto, you end up with the correct answer. 12 divided by 4 equals 3, correct? R = E (12 volts) ÷ I (4 amps). Ohm’s Law – simple! R=EI R = 12 4 R = 3 ohms 21 It’s the Law, per Mr. Ohm! 22 It’s the Law, per Mr. Ohm! 23 Element 2 Technician Class Question Pool It’s the Law, per Mr. Ohm! Valid July 1, 2014 Through June 30, 2018 24 T5A10 Which term describes the rate at which electrical energy is used? A. B. C. D. Resistance Current Power Voltage 25 T5A02 Electrical power is measured in which of the following units? A. B. C. D. Volts Watts Ohms Amperes 26 T5C08 What is the formula used to calculate electrical power in a DC circuit? 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) 27 T5C09 How much power is being used in a circuit when the applied voltage is 13.8 volts DC and the current is 10 amperes? A. B. C. D. 138 watts 0.7 watts 23.8 watts 3.8 watts 28 T5C10 How much power is being used in a circuit when the applied voltage is 12 volts DC and the current is 2.5 amperes? A. B. C. D. 4.8 watts 30 watts 14.5 watts 0.208 watts 29 T5C11 How many amperes are flowing in a circuit when the applied voltage is 12 volts DC and the load is 120 watts? A. B. C. D. 0.1 amperes 10 amperes 12 amperes 132 amperes 30 T5D02 What formula is used to calculate voltage in a circuit? 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) 31 T5D10 What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it? A. B. C. D. 1 volt 0.25 volts 2.5 volts 1.5 volts 32 T5D11 What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it? A. B. C. D. 1 volt 10 volts 11 volts 9 volts 33 T5D12 What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it? A. B. C. D. 8 volts 0.2 volts 12 volts 20 volts 34 T5D01 What formula is used to calculate current in a circuit? 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) 35 T5D09 What is the current flowing through a 24-ohm resistor connected across 240 volts? A. B. C. D. 24,000 amperes 0.1 amperes 10 amperes 216 amperes 36 T5D08 What is the current flowing through a 100-ohm resistor connected across 200 volts? A. B. C. D. 20,000 amperes 0.5 amperes 2 amperes 100 amperes 37 T5D07 What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms? A. B. C. D. 9600 amperes 200 amperes 0.667 amperes 1.5 amperes 38 T5D03 What formula is used to calculate resistance in a circuit? 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) 39 T5D04 What is the resistance of a circuit in which a current of 3 amperes flows through a resistor connected to 90 volts? A. B. C. D. 3 ohms 30 ohms 93 ohms 270 ohms 40 T5D05 What is the resistance in a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes? A. B. C. D. 18 ohms 0.125 ohms 8 ohms 13.5 ohms 41 T5D06 What is the resistance of a circuit that draws 4 amperes from a 12-volt source? A. B. C. D. 3 ohms 16 ohms 48 ohms 8 ohms 42