Physics Electrostatics and Current

Electrostatics and Capacitors

• Electrostatics is the study of stationary electric charges and the forces between them.
• There are two types of electric charge: positive and negative.
• Opposite charges attract, while like charges repel.
• Materials that easily allow electric charge to move through them are called conductors, while materials that resist the flow of charge are called insulators.

Electric Current

• Electric current is the flow of electric charge through a conductor.
• The potential difference (PD) between two points is the work done per unit charge moved from one point to the other.
• The SI unit for potential difference is the volt (V).
• The potential of a point is its potential difference relative to a reference point, often taken to be infinity or ground.
• Electric current flows spontaneously from a higher potential point to a lower potential point if connected by a conducting path.

Ohm's Law

• Ohm's law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature remains constant.
• Conductors that obey Ohm's law are called ohmic conductors, examples include copper and tungsten.
• Non-ohmic conductors do not obey Ohm's law, examples include diodes, LEDs, LDRs, and thermistors.

Resistance

• Resistance is the opposition to the flow of electric current.
• The SI unit for resistance is the ohm (Ω).
• Resistors are devices designed to provide resistance in an electrical circuit, they can be fixed, variable, or potentiometers.
• A thermistor is a temperature-sensitive resistor.
• An LDR (light-dependent resistor) is a light-sensitive resistor.

Electrical Heating

• When electric current flows through a resistor, electrical energy is converted into heat.
• The rate of heat produced is proportional to the square of the current and the resistance.

Electromagnetism

• Electric currents produce magnetic fields.
• Changing magnetic fields induce electric currents.

Electromagnetic Induction

• Electromagnetic induction is the process of generating an electric current in a closed loop by changing the magnetic flux passing through it.
• Faraday's Law of Electromagnetic Induction states that the induced electromotive force (EMF) in a circuit is directly proportional to the rate of change of magnetic flux through the circuit.

Alternating Current Circuits

• Alternating current (AC) is an electric current that varies with time about a mean value, often oscillating sinusoidally.
• An AC voltage is the difference in potential that drives an AC current.
• The peak value of an AC voltage or current is called its amplitude or peak value.
• The frequency of an AC circuit is the number of complete cycles per second, measured in Hertz (Hz).
• The angular frequency of an AC circuit is the rate of change of the phase angle, measured in radians per second (rad/s).

This quiz covers key concepts in electrostatics, electric current, and Ohm's Law. Test your understanding of electric charges, conductors, and potential difference. Perfect for students studying physics at the high school level.