Question

Experimental Setup: Draw/describe how you will make voltage/current measurements in the lab using your orange multimeter (same device as last week).

1. Draw/describe how you will measure the voltage drop across a lightbulb in a circuit. Show/explain where you will put the black lead and the red lead from your orange multimeter and what setting you will have the device on to take this reading.

2. Draw/describe how you will measure the current through a lightbulb in a circuit. Show/explain where you will put the black lead and the red lead from your orange multimeter and what setting you will have the device on to take this reading. (Note: you will have to modify your circuit to make the current measurement because you need put the multimeter in the same wire path as the element through which you want to measure the current.)

Answer 1

1.

1. Set the dial to a voltage value which is greater than the voltage source.
2. Touch the red lead to the wire form the bulb that is connected to the +ve side of the battery.
3. Touch the black lead to the wire form the bulb that is connected to the -ve side of the battery.
4. Read the voltage in the panel. The unit on the dial for voltage is the unit of the output.

2.

1. Switch off the circuit.
2. Switch off the multimeter.
3. Disconnect +ve wire connecting the bulb and the voltage source.
4. Attach the black lead to the bulb's open terminal.
5. Attach the red end of the lead to the open wire connected to the +ve end of the voltage.
6. Set the dial to the maximum amperage rating. (you don't have to set it to 10A, set for conventional values upto 1A or maybe 500mA)
7. Now turn on the circuit, if the reading is too small then lower the knob to a lower value for current and switch on the circuit again. Repeat this till you get a reasonable value.
8. The unit on the dial for current is the unit of the output.