Notes on Electric Circuits and Ohm's Law

Key Concepts in Electric Circuits

• Current in Circuits

• In a series circuit, the current remains the same throughout all components.

• In a parallel circuit, the voltage across each component is the same, but the current can differ depending on the resistance of each branch.

• Potential Difference (PD)

• Potential difference, or voltage, signifies how much energy is being transferred from a power source (like a battery) to the circuit.

• The formula relating voltage (V), current (I), and resistance (R) is expressed as:

  • V = IR

• This relationship shows that voltage equals the product of the current flowing through the circuit and the resistance.

• Calculating Resistance

• The resistance (R) can be determined using the rearranged formula of Ohm's Law:

  • R = V/I

• For example, if a voltage (V) of 4 volts is applied and the current (I) s 2 amperes, then:

  • R = 4V / 2A = 2 Ohms

• Example Calculation

• If you increase the potential difference across a circuit:

  • If the voltage increases from 2 volts to 4 volts with the same current, you can analyze how the components react based on their resistive values.

• If the overall potential difference in a circuit (for example, series connected batteries) is 8 volts, distributed over components, analyze breakdown yields for each branch in the parallel configurations.

• Series vs. Parallel Circuits

• In series, total voltage is the sum of the individual voltages.

• In parallel, total voltage remains constant and equals the voltage across one branch of the circuit which influences individual currents based on varying resistances.

Common Electrical Symbols

• Battery: Symbol for a battery is a long line (+) and a short line (-).

• Resistor: Represented by a zigzag line.

• Capacitor: Two parallel lines (with one longer indicating polarity).

• Lamp/Bulb: Circle with a cross inside indicating the lightbulb.

• Switch: A break in the line indicating an open circuit.

• Ground: Three horizontal lines stacked (one shorter on top).

• Wire: Straight line representing wires connecting components.