Fundamentals of Electricity and Circuits

Electricity

The flow of electric charge (electrons) through a conductor like a wire.

Voltage

The electrical pressure that pushes current through a circuit. It's measured in volts (V).

Current

The flow of electric charge through a circuit. It's measured in amperes (A).

Resistance

How much a material resists the flow of current. It's measured in ohms (Ω).

Simple Circuit

Consists of a power source (battery/cell), wires, a load (like a bulb), and often a switch.

Ohm's Law

Shows the relationship between voltage, current, and resistance: V = I × R.

Voltage formula

(V) = Current (I) × Resistance (R)

Resistance formula

Resistance (R) = Voltage (V) ÷ Current (I)

Current Formula

Current (I) = Voltage (V) ÷ Resistance (R

Effect of changing voltage, resistance, or current

Increasing voltage increases current; Increasing resistance decreases current; Decreasing resistance increases current.

Parallel Circuit

A circuit with multiple paths for current. Components are connected across the same voltage.

Difference between Series and Parallel Circuits

One path, shared current, if one component fails, all stop.

What happens if Series circuit fails

The whole circuit stops working. No current flows.

What happens if Parralel circuit fails

The other bulb still works because it's on a separate path.

Electrical Safety Rules

Don't overload power points, keep cords dry, turn off switches before fixing.

Electrical Safety Devices

Fuses, circuit breakers, safety switches (RCDs).

Fuse

A thin wire that melts and breaks the circuit if current is too high.

Circuit Breaker

Acts as a safety switch that opens when the current is too high

Safety Switch (RCD)

It shuts off power instantly if a current leakage is detected, protecting people from shocks.

Energy Efficiency

How well a device uses energy without wasting it.

Power def in Electricity

The amount of electrical energy transferred or converted per second.. Measured in watts (W).

Importance of Energy Efficiency

It reduces energy waste, lowers bills, and helps the environment.

LED Light Bulb

Energy-efficient, long-lasting, low heat. Works by electrons moving through a semiconductor and releasing energy as light.

Compact Flourescents (CFL)

Energy-efficient bulbs, but less efficient than LEDs. Works through electricity exciting gas in in the tube producing UV light, which hits a flourescent coating to produce light.

Incandescent Light Bulb

Uses more energy, gets hotter, shorter life. Works through a thin metal filament being heated by an electric current until it glows

Energy Loss in Light Bulb

It is common for energy to be wasted as heat in a light bulb

Non-Renewable Resources

Resources that take millions of years to form and will eventually run out (e.g., coal, oil, gas).

Renewable Resources

Resources that can be replaced naturally in a short time (e.g., solar, wind, hydro).

Difference Between Renewable and Non-Renewable Resources

Renewable: endless supply, better for environment; Non-renewable: limited supply, runs out faster than it is consumed

Examples of Non-Renewable Resources

Coal, oil, natural gas.

Examples of Renewable Resources

Solar, wind, hydroelectric, geothermal.

Benefits and Negatives of Renewable Resources

They are cleaner, don't run out, and reduce pollution. They have a higher upfront cost.

AC (Alternating Current)

Current that changes direction regularly (used in homes).

DC (Direct Current)

Current that flows in one direction only (used in batteries).

Difference Between AC and DC

AC: changes direction, high voltage, used in homes; DC: constant direction, lower voltage, used in devices.

Examples of AC and DC

AC: wall sockets, power lines; DC: batteries, phone chargers.

Danger of AC Compared to DC

AC can cause more severe muscle contractions and affects the heart because it alternates direction quickly.