Asst. Prof. Dr. Prapun Suksompongprapun@siit.tu.ac.th

2. Basic Laws

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Basic Electrical EngineeringECS 203

Office Hours: BKD, 4th floor of Sirindhralai building

Monday 14:00-16:00Thursday 10:30-11:30Friday 14:00-15:00

Measuring Resistance

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Measuring Resistance

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Analogy

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Voltage is like water pressure, current (amps) is like the flow rate, and resistance (ohms) is like the size of the pipe.

Increasing the voltage results in a greater current (more amps)—assuming a constant resistance-since increasing the pressure logically increases flow

Ohm’s Law: When V is increased

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Let’s change the load (resistor) to something else

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Ohm’s Law: When V is increased

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Starting with 1V

@ 9V: What’s the mount of current?

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Potentiometer (Pot)

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Pot as a variable resistor

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Manually adjustable resistor

Three terminals

The resistance between the middle terminal and either of the two sides depends on the position of the wiper.

Potentiometer (Pot)

11 [http://educationforengineer.blogspot.com/2013/05/potentiometer-working.html]

resistive strip

Pot as a variable resistor

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Manually adjustable resistor

Three terminals

The resistance between the middle terminal and either of the two sides depends on the position of the wiper.

p = iv and v = iR

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Overheating Resistor

14 [https://www.youtube.com/watch?v=0EmRY6s0UPk]47 resistor under 4W

Overheating Resistor

15 [https://www.youtube.com/watch?v=ZHv6VkKBPGA]

How to pronounce Kirchhoff?

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KCL

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Elements in one loop: KVL

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Voltage sources in series

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Voltage sources in series

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Voltage sources in series

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Voltage sources in series

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AAAA battery (usually read as quadruple-A)

(almost… they are 3.5 mm shorter)

Inception?

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Wow!Batteries within a battery

AAAA battery

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Surface Pen

Voltage sources in series

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Voltage sources in series

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Voltage sources in series

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12V “Car Alarm Remote” Battery

Voltage sources in series

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