Ohms Law, current electricity, series circuits

Electric Current The continuous flow of electrons through a conducting metal.

Alternating Current Flow of current that periodically changes direction Produced in power plants Current from a wall outlet changes direction 120 times per second

Direct Current The flow of current in one consistent direction Examples Batteries Solar cells Current from a battery travels from the positive terminal to the negative terminal.

Common Language

Note Taking Guide Quantity Symbol Definition Unit Measuring Device voltage current resistance

Voltage Voltage (V) (also know as Potential Difference) can be thought of as the force pushing electric charges along a conductor. It is the energy in the circuit Measured in Volts (V)

electric potential difference, must be connected in parallel Voltmeter a device that measures electric potential difference, must be connected in parallel

Current Electric current (I) is the movement of electric charge in a conductor (rate at which the electrons are flowing) Measured in Amps (A)

a device that measures current Ammeter a device that measures current attached in series

Resistance Resistance (R) is a measure of how difficult it is to push the charges along. The energy is transformed at the resistor (potential energy is converted). Examples: light bulb, charging your phone, making coffee, etc. Measured in Ohms () An Ohmmeter is used to measure resistance in a system.

Note Taking Guide Quantity Symbol Definition Unit Measuring Device voltage V Energy in the circuit Volts Voltmeter current I Rate of flow Amps Ammeter resistance R Opposes current; energy transforms OhmsΩ Ohmmeter

Ohm’s Law Ohm's Law analyzes the relationship between voltage and current in an ideal conductor. Ohm's Law is given by: V = I * R

Example A flashlight that is powered by 3 volts and uses a bulb with a resistance of 60 ohms. What is the current flowing through the circuit?

Example A flashlight that is powered by 3 volts and uses a bulb with a resistance of 60 ohms. What is the current flowing through the circuit? G: V = 3 volts E: V = (I)(R) S: 0.05 Amps R = 60 Ω S: 3 = (I)(60) U: I

Practice

Series Circuits Resistors can be connected in series; that is, the current flows through them one after another.

Kirchhoff’s Rules Loop Rule: The sum of the potential differences (voltage) around any closed circuit loop is zero.

Kirchhoff’s Rules Loop Rule: The sum of the potential differences (voltage) around any closed circuit loop is zero.

Series Circuit RT = R1 + R2 + R3 + ... IT = I1 = I2 = I3 = ... 1. total resistance is the sum of the separate resistors RT = R1 + R2 + R3 + ... 2. current is the same through each resistor IT = I1 = I2 = I3 = ... 3. total potential difference is the sum of each VT = V1 + V2 + V3 + ... In other words, in a series circuit, resistance and voltage add, but current stays the same.

Series Circuit Example

Series Circuit Practice