1. Meter Lab Introduction to Electricity Assignment for tomorrow: Read chapter R1

2. Electric Current Electric current is the flow of charge, the number of electrons that pass a given point in a second. The unit of current it the amp. One amp is one Coulomb (a unit of charge) per second

3. Voltage Voltage is potential energy per unit of charge. Charge is measured in units called coulombs. One volt is one joule/coulomb

4. On the care of Multimeters These meters are battery driven, so always turn them off as soon as you finish with them. The greatest damage is done when the meter is set to measure current and you put the leads across a voltage source, such as the wall socket or even a battery. –To protect the meter, some multimeters require that you move a lead to measure current, but not all.

5. Ohm’s law Links the voltage and the current (through the resistance) V=IR One ohm of resistance is one volt per amp. Voltage Current Resistance

6. Direct or alternating current In direct current the electrons are always going the same direction. The symbol is often a straight line; V¯ for voltage in a circuit with direct current. In alternating current the electrons move forwards, then backwards. The symbol is often a wavy line; V ~ for voltage in a circuit with direct current. Batteries are always direct current. The wall socket is always alternating current.

7. The polarity of batteries Positive (+) Negative (-) This type of battery is often used in calculators, watches, etc.

8. Resistance color codes: Band 1 = first digitBand 2 = second digitBand 3 = multiplier Band 1 = green = 5 Band 2 = blue = 6Band 3 = yellow = 10k R = 56 x 10,000 = 560,000 Ω = 560k Ω ± 5%

9. For your safety and for the safety of the equipment always have the instructor check any circuit before making the final connection. This is especially true if some equipment is to be plugged into the wall socket. Using a volt meter in place of an amp meter or a volt setting in place of an current setting will do no harm. If an ammeter is connect across a voltage (including a battery) it could ruin it.