Circuits Fundamentals: Cells and Voltmeters

Laboratory Activities

Purposes:

1. To observe the difference in total voltage when batteries are connected in series and in parallel.

2. To learn how to properly use a voltmeter to measure voltage in a circuit

Materials & Apparatus:

• batteries and battery holders

• voltmeter

• connecting wires with alligator clips

• switch (optional)

Procedure:

a) single cell

1. Set up the following circuit diagram

2. Draw the equivalent circuit diagram using proper symbols

3. Measure the voltage across the battery or batteries

4. Record the value of voltage

Voltage = __________________

b) two cells in series

Repeat steps 1 to 4 above

Voltage = __________________

c) two cells in parallel

Repeat steps 1 to 4 above

    Voltage = __________________

Questions:

1. What are the general rules for connecting voltmeters in a circuit.

2. What can you conclude about the total voltage when cells are connected in series?

3. What can you conclude about the total voltage when cells are connected in parallel?

4. What would the total voltage be if you connected two cells in series as shown:

5. Draw a circuit diagram including a voltmeter and calculate the total voltage for each of the following circuits of cells (as measured by the voltmeter).

1. two 1.5 volt cells in series

2. two 1.5 volt cells in  parallel and one 3.5 volt in series

3. three 2.5 volt cells in parallel