Parallel Circuits Experiments
Electrical components or devices are parallel to each other when they are connected to the same two points. For resistive devices that obey Ohm's Law, the current is divided among them, but they share the same voltage. Parallel circuits are common in everyday use because when one device in the circuit is no longer operational, the others are not affected. This is opposite to that of a series circuit, in which one faulty component means all the others stop working as well. The wiring inside buildings is usually constructed for parallel devices.
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Resistors in Parallel
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Obtain a battery and two resistors of different values. For example, use one or two AA batteries connected to a 10 ohm and 100 ohm resistor. Use a multimeter and measure the voltage across each resistor. Do this by placing the multimeter on the voltage setting and then placing one probe across each lead of the resistor. If you have used an ammeter before, place the multimeter on the current setting and make sure the probes have alligator clips attached. Wire the multimeter in series with the first resistor. Record the current. Repeat for the second resistor. In a parallel circuit, resistors have the same voltage but different currents. The formula for two of them is Iin = I1 + I2, where I1 is the current for the first resistor and I2 is the current for the second.
Mini-lamps in Parallel
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Purchase two or three low voltage mini-lamps. Some may be bought online or in electronics stores for 1.5 to 6 volts. Connect the mini-lamps in parallel to the proper voltage, such as one or two AA or 6 volt batteries. What happens if you disconnect one lamp from the circuit? What happens to the voltage if you add one more mini-lamp?
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Capacitors In Parallel
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Capacitors may also be used. Obtain non-polarized ones such as the yellow mylar cylinders or the orange ceramic disc capacitors to practice with. If you use polarized ones instead, be sure to wire them properly or they will be destroyed. Capacitors in parallel will reach the same voltage when connected to a battery. Connect two or three in parallel with a 1.5 to 3 V battery. Allow a few seconds for the capacitors to charge, and then record the voltages across each one. Disconnect the battery and wait for the capacitors to discharge. Measure the voltages again. You may wish to use a switch before each capacitor to charge and discharge each one individually.
Other Circuits
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Other components that may be wired in parallel with each other include low voltage solar cells or batteries.
Warning
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Do not wire the ammeter in series with a circuit if you have not used one before. You may blow a fuse or damage your equipment if you use it improperly. Since capacitors store charge, never use a high voltage power source to conduct your experiments. You may risk electric shock and destruction of your devices.
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References
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