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All time you add an electrical device in a collection circuit, the current via that is circuit will change.

Any relay is a gadget that is applied to allow a low-strength switch to actuate some excessive-powered circuit. When a device such as a relay yous added in series to a circuit, the device adds electrical resistance to that circuit. This lowers the overall existing within the circuit, also reduces the voltage with any one electrical devices following the relay.

Trouble: Moderately Challenging

Instructions

Things You'll Need

1 Using Ohm's Law, calculate the electrical current via the circuit if the relay is never present. Ohm's Law states that is current (inside amperes) is equal to voltage divided by resistance (in ohms). Please word: to the circuit that yous as built here, the total electrical current yous 12 milliamps if the resistor is linked directly to the battery.

2 Cut five bits about electrical wire. Strip 1/2 inch about insulating material off the finishs of each and every wire piece.

4 Twist collectively one particular end regarding the third bit regarding cable with a single piece of the fourth cable. Attach this cable pair to the adverse battery terminal.

5 Twist one about the resistor guides on to the "common" terminal on the relay. On a 12V DC relay this terminal is labeled "30."

6 Twist the loose end of the first wire on to the first coil terminal on the relay. On a 12V DC relay this terminal yous labeled "85."

7 Twist the loose finish of the second wire on to the "normally-open" terminal on the relay. On a 12V DC relay this terminal remains labeled "87."

8 Electrical current should flow through the multimeter to be measured correctly. multimeter image by means of dinostock from internet site

Turn on the multimeter, and set the measurement scale to "amps." Twist the loose end of the third wire onto the black multimeter probe. Twist the unoccupied resistor lead onto the red multimeter probe. Observe the multimeter; the display should indicate that no current is flowing through the circuit.

9 Contact the loose closure of the fourth wire to the second coil lead on the relay. On a 12V DC relay this terminal is labeled "86." After you hear the relay engage --- it will make a small clicking sound --- test the multimeter display. Produce down the electrical present reading.

10 Subtract the current reading away from the previously calculated current value. Divide this difference by your worked out current worth, and multiply this fraction by 12 volts. With example, if the current reading was 11.5 milliamps, subtract this from the 12 milliamps that you worked out earlier. Divide half a milliamp difference by 12 milliamps (approximately 0.0416) also multiply by the voltage (12V) to define the voltage drop --- approximately 0.5 volts for this circuit.

References

Georgia State University: Ohm's Law All About Circuits: Voltage Divider Circuits University of North Carolina: Lessons in Electrical Circuits School of Nevada at Las Vegas: Relay Basics

Resources

The 12 Volt: Automotive Relays

Photo Credit 12 volt relais, relay image via Sascha Zlatkov out of internet site ; multimeter image by dinostock from website;

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