# Hands-On-PhysicsELECTRICITY

## - Electronic Components -

This list is a description of what the various components do. If you would like more detailed information about how they work, refer to an electronics textbook.

Switches These make contact between two wires or break contact between two wires. The spring loaded switches are classified as normally open (NO) or normally closed (NC). NO switches have the connection open, or broken, unless the switch is pushed. NC switches have the connection closed unless the switch is pushed.

Resistors These provide resistance to the flow of electric current. The larger the resistor, the more opposition to current it provides. In doing this the resistor reduces the voltage of the electrons passing through it, and that energy is let off as heat. So an overloaded resistor gets hot, and can even melt (this is smelly) or burn (even smellier).

Bulbs Light bulbs convert electric current into heat. The filaments get so hot they glow and produce light. Light bulbs are resistors, but beware, their resistance get higher as they get hotter. Interesting.

Transistors These act as switches which can be turned on and off electronically. Large amounts of current are controlled by very small currents. Normally a transistor provides very high resistance between the collector and the emitter; it allows no current through. However, once there is a small current through the base to the emitter, the resistance between the collector and emitter plummets, allowing current to flow.

Bridge Rectifiers These are collections of four diodes. Each diode allows current to flow in only one direction. The four diodes are put together so that alternating current, which goes from positive to negative, is only allowed to oscillate only between zero and a positive number. When the current goes negative, it is flipped to become positive.

Voltage Regulators These permit only voltages up to a maximum. Any voltage above the maximum is chopped off and extra energy is dissipated as heat. Therefore, you should always have a heat sink on a voltage regulator.

Capacitors These store electrical energy when electrons are "pumped" off one plate of the capacitor (leaving it positively charged) and onto the other plate (making it negatively charged). When the charging voltage is removed after the capacitor is charged, the capacitor can push the electrons back through into circuit. This results in smoothing out peaks and valleys in a varying voltage. The larger the capacitor, the more energy it can store. The electrolytic capacitors will POP and be destroyed if they are connected backwards. Read more about capacitors.

Potentiometers Dimmer switches are potentiometers. Potentiometers (pots) provide a variable resistance; twisting the shaft changes the resistance to allow more or less current through. This should control the brightness of the light bulb, the volume of the buzzer, or the amount of voltage at the output of your LVPS.

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