Introduction to Robotics/Electrical Components/Lab/Teachers
Lab (For Students) (For Teachers) — Assignment (For Students) (For Teachers) — Quiz (For Students) (For Teachers)
Preparation
Each group of students is going to need the following components:
- Breadboard
- Voltage/current/Ohm meters, or a DMM
- Power supply
Lecture Part
We want to introduce the electrical equipment, and demonstrate how to use the meters to measure voltage, current, and resistance.
Measuring Circuits
When measuring various circuit quantities, make sure to reiterate these points:
- Measure voltage across an element.
- Measure current at a break in the circuit, never across an element.
- Take care not to short your circuit with your probes and wires.
In terms of safety, it is important to reiterate this point: 2 amps of current is enough to kill a person. 1 amp of current is enough to injure a person. When working with circuits, make sure students understand not to play with the power source, and to always use appropriate resistance to keep their current under control.
Current Meters
Some students will want to know why we must break a circuit to measure the current. Repeat the point that an Amp-meter has zero resistance. Point out that the power supply is at a constant value, such as 5 volts. Now, ask the student:
- You have 5 volts and 0 Ohms resistance, what is the current?
Let the student think about it, and if they appear confused, repeat for them Ohm's law: V = I R. Let the student try to solve the equation on paper, if needed, but let the student come to the solution on their own: With zero resistance, the amount of current going through the ammeter will approach infinity, and infinity is bad.