Ohm's Law and Electric Circuits

Ohm's Law

• An electric circuit forms a closed loop from one battery terminal to the other, enabling current to flow.
• Charge moves from higher to lower potential energy.
• Ohm's Law relates voltage (V), current (I), and resistance (R).
• Current (I) in a circuit is directly proportional to voltage and inversely proportional to resistance.
• Formula: V = IR, I = V/R, R = V/I
• V = Voltage in Volts (V)
• I = Current in Amperes (A)
• R = Resistance in Ohms (Ω)

Electric Quantities in a Circuit

• Voltage (V) is the electrical pressure pushing electrons through a conductor, measured in Volts (V).
• Higher voltage means a stronger push for current.
• Current (I) is the flow of electric charge in a circuit, measured in Amperes (A).
• Alternating Current (AC) periodically reverses direction whereas Direct Current (DC) flows in only one direction.
• Higher current means more electrons are moving.
• Resistance (R) resists the flow of charge, measured in Ohms (Ω).
• More resistance results in less current.
• Resistors reduce the potential energy of charge flowing through them.

Relationships Among Voltage, Current and Resistance (VIR)

• Voltage and current are directly proportional but only if resistance is constant; if voltage increases, current increases, and vice versa.
• Resistance and current are inversely proportional when voltage is constant; if resistance increases, current decreases, and vice versa.
• Thinner wires have more resistance, resulting in decreased current flow
• With constant current, resistance and voltage are proportional; if resistance increases, voltage increases to maintain current and vice versa.

Effective Resistance in Electrical Circuits

• In a series circuit, there is a single pathway for current, whereas a parallel circuit has one or more pathways.
• Series Circuit Formulas: V total = V1 + V2 +... + Vn and I total = I1 = I2 =... = In and R total = R1 + R2 +...+ Rn
• Parallel Circuit Formulas: V total = V1 = V2 =... = Vn and I total = I1 + I2 +... + In and 1/R total = 1/R1 + 1/R2 +...+ 1/Rn

Electrical Safety at Home

• Fuses melt when current is too high, stopping electricity flow.
• Circuit breakers automatically trip when current overloads, preventing damage.
• GFCIs cut power when a ground fault is detected, typically used in wet areas.

Safety Tips for Handling Electricity

• Keep water away from electrical devices.
• Replace frayed or damaged cords and plugs.
• Avoid overloading outlets.
• Unplug devices when not in use.
• Use grounded plugs.
• Stay away from power lines.
• Utilize circuit breakers and fuses.
• Keep electrical devices ventilated.

Proper Use of Electrical Appliances

• Always follow the manufacturer's instructions.
• Keep appliances dry and away from flammable materials.
• Pull plugs from the base, not the cord.
• Ensure adequate ventilation for high-power devices.