# Schematic Diagrams

1. Jan 25, 2006

### chemistrykid

Q: Use symbols to draw a circuit diagram showing two dry cells connected in parallel with each other, and in parallel with two light bulbs. Show a voltmeter connected to measure the electrical potential of the two dry cells and an ammeter to measure electrical current through one of the bulbs.

A: The thing that trips me up about this question is the parallel with two light bulbs. I understand how to connect two dry cells in parallel but how do you add the light bulbs in?

2. Jan 25, 2006

### Staff: Mentor

Connecting two batteries (or other voltage sources) in parallel is a bad idea. Good way to start a fire. Whatever.

Draw a horizontal line at the top of the page and one at the bottom of the page. These will be your V+ and Ground rails, respectively. For each battery, connect the + lead to the top line and the - lead to the bottom line. (Optional -- Add a note to the drawing that this is a bad way to connect batteries.) Then connect each light bulb between the two rails. Connect the voltmeter + lead to the top rail and the - lead to the bottom rail. To show the ammeter, erase part of the line between the left light bulb and the + rail, and draw a circle to represent the ammeter there. Connect the + lead of the ammeter to the top rail, and the - lead to the top lead of the light bulb.

Quiz Question -- Why is it a very bad idea to connect the two batteries in parallel?