Electric Current Introduction

What would happen if you put a small positive charge between two plates? + + + + + + + + + + + + + + + + + + + + + + + + high potential (high energy per charge) + – – – – – – – – – – – – – – – – – – – – – – – – low potential

What if you just connected the two plates with a metal wire? + + + + + + + high potential (high energy per charge) + + + + + + + + + + + + + + + + + current + charge will flow from high potential to low potential until plates are neutralized. – – – – – – – – – – – – – – – low potential – – – – – – – – –

Electric Current The rate of flow of electric charge. Measured in C/s or Amps (A). Conventional current is defined to be the direction of flow of positive charge.

How could you make the flow of current constant? + + + + + + + high potential (high energy per charge) + + + + + + + + + + + + + + + + + DO WORK! – – – – – – – – – – – – – – – low potential – – – – – – – – –

Vocabulary Voltage (V) – aka electric potential difference [Volts – V] Current (I) – rate of flow of charge [Amps – A] Direct current (dc) – same direction all times Alternating current (ac) – changes direction Resistance (R) – how much the flow of charge restricted [Ohms – Ω] ρ = resistivity [Ω∙m] L = length [m] A = area [m2] Copper has a very low resistance which is why it is often used for wiring.

What is the relationship between voltage, current, and resistance? Use what you know about finding mathematical relationships to find “Ohm’s Law” with a rheostat.

Power