Energy is the ability to do work and is measured in joules (J).
People use energy to run, plants need energy from the sun to continue living, cars need energy from fuel to move, and light from a bulb is produced by energy.
Energy cannot be created nor destroyed and can exist in various forms such as:
sound energy
kinetic energy
electrical energy
gravitational potential energy
elastic potential energy
nuclear energy
light energy
heat energy
chemical energy.
Electric shock when touching a grocery trolley is due to the transfer of electrostatic charges between our body and the trolley.
Electric charges consist of positive charges (protons) and negative charges (electrons), and attraction and repulsion between them are known as electrostatic forces.
When two different objects are rubbed together, only electrons are transferred, resulting in one object becoming negatively charged and the other positively charged.
A comb rubbed with a woollen cloth gains electrons and becomes negatively charged, attracting pieces of neutral shredded paper.
An electroscope is a device used to detect the existence of electric charges on an object, with the gold leaf diverging due to the repulsion between like charges.
Examples of electrostatic in daily life include the charging of clouds through friction with air, resulting in lightning, and the use of lightning conductors to provide a path for electric charges to flow into the ground.
Electric current is the rate of flow of electric charges through a conductor, measured in amperes (A).
Voltage is the potential difference between two points, measured in volts (V).
Resistance is the ability of a conductor to limit or resist the flow of electric current, measured in ohms (Ω).
Ohm's Law states that the electric current (I) is directly proportional to the voltage (V) across a conductor, provided the temperature and other physical situations remain unchanged.
Ohm's Law equation: V = IR, where V is voltage, I is current, and R is resistance.
A series circuit is made up of electrical components that are connected one after another where the current flows through in a single path.
In a series circuit, the current is the same through all components, the voltage is the sum of the individual voltages, and the resistance is the sum of the individual resistances.
In a series circuit, the effective resistance is the sum of the individual resistances.
In a series circuit, the current can be calculated using Ohm's Law (I = V/R).
In a series circuit, the voltage across each component can be calculated by multiplying the current by the resistance of the component.
Advantages of a series circuit include every component receiving the same amount of current and an increase in voltage supplying more electric current.
In a series circuit, I = I1= I2=...
In a series circuit, V = V1 + V2 + ...
In a series circuit, R = R1 + R2 + R3 + R4
The total resistance of a series circuit is equal to the sum of all resistances.
A parallel circuit has multiple paths for electricity to flow through.
In a parallel circuit, I = I1+I2+... (total current)
In a parallel circuit, V = V1=V2=... (voltage across components)
In a parallel circuit, 1/Rt = 1/R1 + 1/R2 + 1/R3 + 1/R4
In a parallel circuit, the voltage remains constant throughout the circuit.
In a parallel circuit, if one branch breaks or opens, it does not affect other branches.
A parallel circuit is separated into several different paths of electrical circuit and each parallel path has electrical components.
The voltage in a parallel circuit is the same across each component.
Advantages of a parallel circuit include the ability to switch on or off each electrical appliance separately and the function of other appliances not being affected by the addition of more appliances.
The current in a parallel circuit can be calculated by dividing the voltage by the resistance.
Van de Graff generator: A device that produces a constant voltage by applying a constant current to a wire that is suspended in a container of air.
Conductor: An object through which electricity flows easily.
Insulator: An object that resists the flow of electricity.
Resistance: The measure of how difficult it is for an electric charge to move through a material.