Introduction to Circuits

(Download the MS Word version of this document.)

Materials

• Four "D" batteries
• Wires
• Two light bulbs (Holiday lights can be used)
• Voltmeter

Procedure

1. Measure and record the voltage across each battery. Your batteries are arranged in a tube. To measure the voltage across each battery, attach the voltmeter to the metal clips on each end of the individual battery. (Don't forget units.)

(1) __________ (2) ____________ (3) ___________ (4) ___________

Draw a sketch of how you connected the voltmeter to the battery. The schematic diagrams will be completed later in the lab.

sketch

schematic diagram

(b) Light the bulb with two, three, and four batteries. What happens to the brightness of the bulb as you add batteries? Why?

3. (a) Using four batteries, two light bulbs, and wires connect a circuit in such a way that both bulbs are lit but when one bulb is disconnected (and it goes out), the other bulb also goes out.

(b) Use the voltmeter to measure the voltage across each bulb individually when both are lit, and record the voltage across each.

(1) _______________________ (2) ____________________________

(c) Draw a sketch of your circuit, including the voltmeter.

sketch

schematic diagram

(d) If this circuit only had one bulb, would its brightness be brighter or dimmer than the brightness of either of the two bulbs connected in this circuit? Why?

4. (a) Using two batteries, two light bulbs, wires, connect a circuit in such a way that when you disconnect one bulb (and it goes out), the other bulb does not go out.

(b) Use the voltmeter to measure the voltage across each bulb individually when both are lit.

(1) _______________________ (2) ____________________________

(c) Draw a sketch of your circuit, including the voltmeter.

sketch

schematic diagram

(d) If this circuit only had one bulb, would its brightness be brighter, dimmer, or the same brightness as either of the two bulbs when both are connected in this circuit? Why?

6. For each circuit sketch above, go back and draw the schematic diagram next to each physical diagram using the symbol for each element in the circuit. Use a ruler to draw straight lines.