Electrical energy follows several physical laws. One of these laws, Kirchhoff’s Voltage Law, explains that the sum of the voltage drops around a closed circuit loop must equal zero. In a circuit with multiple electrical resistors, the voltage will drop at each resistor electrical joint. This can be useful if you need to obtain five volts from a 12-volt power source.
- 12-volt DC power supply
- 1.4-kiloohm resistor
- 1-kiloohm resistor
- Electrical wire
- Electrical pliers
Electrical resistors can vary in quality. The resistance value of a metal-film resistor is accurate to within 1%. Carbon-film resistors are accurate to within 5% tolerance, while the resistance of a wirewound resistor can vary as much as 10%.
Cut two pieces of electrical wire. Strip ½ an inch of insulation from the ends of each wire. Verify that the power supply is turned off.
Twist together one end of the first wire with one of the leads from the 1.4-kiloohm resistor. Connect the loose end of this wire to the positive terminal on the power supply.
Twist together the free lead from the 1.4-kiloohm resistor with one of the leads from the 1-kiloohm resistor.
Twist together the free lead from the 1-kiloohm resistor with one end of the second wire. Connect the loose end of this wire to the negative terminal on the power supply. Turn the power supply on
Turn on the voltmeter and set the scale to measure "Volts DC." Place the black voltmeter probe on the electrical joint between the second wire and the 1-kiloohm resistor. Place the red voltmeter probe on the electrical joint between the two resistors. The voltage across the resistor will be approximately 5 volts.
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About the Author
David Sandoval holds a degree in microelectronics, and has several years of experience in the technology field. He has written articles for eHow, Answerbag, and wiseGEEK in the disciplines of chemistry, electronics, and physics.