Lesson Plan Industry Sector
Transportation

## **Use of a Multimeter (updated) By Michael Drouin

### Lesson Plan Overview / Details

Students will utilize a multimeter to check Voltage, resistance, current, and continuity.

Classroom/Lab
1 Day

### Objectives/Goals

Students will be able to:

• Utilize a multimeter
• Choose the correct settings to measure volts, amps, and resistance
• Understand the purpose and function of volts, amps, and resistance

### Activities in this Lesson

• I start class with a multimeter (DVOM-digital volt ohm meter) in hand and review Ohm's law. I inform the students that you need a volt meter to check voltage, an ohm meter to check resistance, and an amp meter to check current. This meter does all three and is why we call it a MULTI-meter!

• Attention Grabber - Hooks / Set

I then tell the students this: "It's a little-known fact" (joke to get attention) "that it can also measure brain density/intelligence."  I then instruct the students to do the following:

- Set the meter to resistance.

- Make sure your fingers are in contact with the probes and touch them to your temple.

- I then allow a student to read the number on the meter (it will read a number).

- I then tell the students that if it is a 4.0 (what ever the number is) that's pretty smart. Then I ask another student to do the same with their meter. The numbers will vary until one student will just touch the probe to temple and it will read 0.0 I give him a blank stare, take the probes and check mine again to make sure it still shows a number then have him check again...the light is on, but nobody is home or some other appropriate joke.

- If done correctly, this will get a few laughs and get everyone focused on what you are doing.

• Visual lesson - Lecture

I then put an overhead up that shows the front of the meter, and tell/show them it is the same as the meter in my hand. Next I ask what is the first thing in ohms law. Student will say volts. I then answer "Good, but remember that we have two types of voltage," and ask students, "What is the other type?"

• DC Volts - Demo / Modeling

I continue to lecture the students and inform them that volts DC is the type from a battery. It has the electrons only move one direction, and when they have all moved, the battery is dead. I then point to the Volts DC setting on the overhead, draw the Volts DC symbol on the board, switch the meter to the Volts DC position and walk around and show it to the students. Then walk over and take a reading (use a battery in a car) I ask (a student) what is the voltage on a car battery. Then connect it and show them the reading (12 volts), then walk to the board and draw the correct connection to check Volts DC.

• AC Volts - Demo / Modeling

I then discuss Volts AC and tell them that volts DC will not work on the lights (point up to the classroom lights) because they have no place to store the electrons. So we alternate them-- send them out, then send them back, which is known as Volts AC. I tell the students that the first guys to figure this out were from Australia...you know AC/DC (the rock group). I put the meter on Volts AC, point to it on the overhead and walk around showing students. Then check the volts in the wall socket (120V). I then usually ask who stuck something in the socket as a kid??? Will the voltage kill you? (Yes.)

• Resistance - Demo / Modeling

Point to the resistance position on the overhead, switch the meter to the resistance position, show students the meter.

As the electrons flow through anything, they meet resistance. I hook up and check the resistance on a couple of things (wire etc. what ever you have).

I draw the correct connection on the board. Explain to make sure voltage is off when checking resistance.

This is a good time to point out that you cannot measure intelligence, only the resistance your body has (the joke).

• Current or Amps - Demo / Modeling

Point out position on overhead, switch meter to amps. Explain the difference in connecting meter for measuring amps (must run through the meter). Walk around and show students, and then draw how you connect the amp meter on the board.

• Continuity - Demo / Modeling

One other thing the multimeter will do is it will check continuity. Show on the overhead the continuity position, switch meter to continuity position then demonstrate that it beeps when probes are touched. Explain that this is used to check if the circuit is complete, open, short to ground, short to power.

Demonstrate electrical connection on several items or your choice. I use a couple of wires. The last example I use is a large metal table, where I can demonstrate a physically large circuit.

• I will now review ohms law and the use of the multimeter, and hand out the work/lab sheets with the students. The students will then have to refer to their work/lab sheets in order to select the correct position on the multimeter. The color in the LCD will represent what is displayed. Students wll then utilize the worksheet and a computer to view the ...... CD which also covers information about the Fluke meter. I will then finish by discussing the different types of meters (Fluke, etc.), cost, and where they can be purchased. I will remind the students to turn off the meter when they are done using it because if they fail to do so, the battery can run dead.

### Assessment

Assessment Types: