Notes, summaries, assignments, exams, and exercises for Physics for Secondary education

Electromagnetic Waves

Electromagnetic waves are electromagnetic field disturbances generated by moving charges in the presence of a magnetic field. The electromagnetic material does not need a medium to propagate. Its speed is nearly 300,000 km/s.

Examples of Wave Applications

Common examples include the waves used for television and radio, mobile phones, or satellite links.

The Electromagnetic Spectrum

All sorts of electromagnetic waves are categorized within the electromagnetic spectrum. This includes visible light emission with a wavelength between 700 and 380 nanometers.

Spectrum Regions

• AM Radio
• Television
• Radar
• Infrared
• Visible Light
• Ultraviolet (UV)
• X-rays
• Gamma rays

Properties of Sound

• Intensity: This is proportional to the amplitude of the wave. Strength

Energy: Units and Types

• Unit of energy: Joule (J)
• Conservation of Energy: Energy cannot be created or destroyed, only transferred or transformed.
• Kinetic Energy: Energy of motion.
• Potential Energy: Stored due to position (e.g., at the top of a pendulum).

Conduction

• Occurs mainly in solids.
• Particles transfer energy by vibrating and passing it to neighbors.
• Metals are good conductors.
• Poor conductors (insulators), e.g., air and layers of clothing.

Convection

• Happens only in fluids (liquids and gases).
• Heated fluid becomes less dense → rises.
• Cooler fluid becomes more dense → sinks.
• Creates convection currents.
• Example: Hot water in a pan rises to the top.

Radiation

• Transfer by infra-red waves.
• Only method that works in a vacuum (space).
• Best absorber/emitter:

Understanding Electrical Principles and Circuits

Static Electricity Fundamentals

When an atom becomes an ion, it becomes charged. When two insulating materials are rubbed together (e.g., wool and a plastic rod), electrons move from one material to another (as protons cannot move). This process results in one material becoming negatively charged and the other positively charged. Once charged, these materials can attract uncharged objects and objects with an opposite charge.

Understanding Electrical Sparking

A significant charge builds up on one object due to electrons being rubbed off by another. If a large enough charge accumulates, the voltage becomes sufficiently high to ionize the air molecules. This allows electrons to jump to earth, causing...

Photons and Electrons in the Double Slit Experiment

Evidence for Wave-Particle Duality

• A single electron or photon leaves the source with particle-like discreteness and creates a single discrete spot on the screen.
• The interference pattern, which occurs over time, is a wave property.

Diffraction Pattern and Heisenberg’s Uncertainty Principle

• We cannot measure the exact position of each electron or its exact momentum as it approaches the slit; there is uncertainty in both position and momentum.
• The uncertainty in each electron’s y-position is reduced to the width of the slit (since we are certain it passes through the slit). This increases its uncertainty in the momentum of the y-direction.
• The uncertainty in the momentum in the y-direction means

Simple Microscope

A simple microscope, commonly used by watch repairers, allows for the observation of minute details by magnifying an object placed within its focal length. The convex lens of the microscope produces an erect image on the same side of the lens as the object. By adjusting the distance between the object and the lens, the image can be obtained at the distance of distinct vision, enabling clear observation without straining the eyes.

Dispersion of Light

The phenomenon of splitting light into its component colors is known as dispersion of light. The band of colored components of a light beam is called a spectrum. The different colors of light in the spectrum of white light are violet, indigo, blue, green, yellow, orange, and red.

Ozone

Sound:

Pressure waves produced when an object vibrates at a frequency between 20 Hz and 20000 Hz and there is a material medium that sound can travel through.

Chapter 1: Electromagnetics Fundamentals

Gauss's Law

Gauss's Law for Electricity: The total electric flux out of a closed surface is equal to the charge enclosed divided by the permittivity ($\epsilon_0$).

Gauss's Law for Magnetism (Eq. 6.3): This integral is zero because magnetic field lines always form closed loops; magnetic monopoles do not exist.

Gauss's Law for Electricity (Eq. 6.1): This integral can be non-zero since positive and negative charges can be isolated, leading to the surface integral equaling $Q$, the enclosed charge.

Wave Characteristics

The velocity with which the envelope—or equivalently the wave group—travels through the medium is called the group velocity.

A traveling wave is characterized by a spatial wavelength ($\lambda$...

Electrical Measurement Devices

A multimeter (often referred to as a "tester") is a versatile device used to measure various electrical quantities, including voltage (both AC and DC), current, and resistance.

Circuit Measurement Techniques

• Measuring Voltage

  To measure voltage, the multimeter is connected in parallel across the two points where you want to determine the potential difference.

• Measuring Current

  To measure current (intensity), the multimeter is connected in series, inserted directly into the circuit path where you want to know the current flow.

Understanding Polarity

When taking measurements in a live circuit, the device's pointer might move in the opposite direction or indicate negative values. This occurs if the multimeter's positive...

Understanding Electromagnets

An electromagnet is a temporary artificial magnet that produces a magnetic field when an electrical current flows through it, which disappears when the current stops. Its advantages include:

• Controllability: Intensity can be adjusted by varying the current.
• Coil Density: Magnetic strength increases with the number of solenoid turns.
• Polarity: Can be reversed by changing the direction of the current flow.

The Solenoid or Coil

A solenoid is a conductor wound in spirals, forming a helix. When electric current flows through it, the solenoid generates an intense magnetic field in its interior, with lines of force parallel to the solenoid's axis.

Electrical Charge

Electrical charge is an intrinsic property of subatomic particles...

Fundamentals of Motion

Movement: A body is in motion when it changes its position relative to a fixed reference point.

• Mobile: The body that is moving.
• Trajectory: The path taken by the mobile from the point of departure to the point of arrival.
• Displacement: The line segment connecting the starting point to the arrival point. It represents the net change in position and does not generally coincide with the trajectory.

Velocity and Acceleration

Speed: The quotient of the distance traveled divided by the time spent. It is expressed as a unit of length divided by a unit of time.

Acceleration: The change in velocity experienced by a body per unit of time. In the SI system, acceleration is measured in meters per second squared (m/s²).

Gravity (g)

The force...