How are waves made?
Waves are made when something vibrates, causing particles or fields to move back and forth and transfer energy.
This process involves the transfer of energy through the medium.
What do waves do?
Waves transfer energy, not matter.
This is a fundamental characteristic of all types of waves.
What is a transverse wave?
A wave where the oscillations are at right angles to the direction the wave travels.
Examples include light waves and water waves.
Examples of transverse waves
- Light waves
- Water waves
- Waves on a rope
These waves exhibit perpendicular motion relative to their direction of travel.
What is frequency and how is it measured?
Frequency is the number of waves per second. Measured in Hertz (Hz).
Higher frequency indicates more waves passing a point in a given time.
How do we see things?
Light reflects off objects and enters the eye. The retina detects the light and sends signals to the brain to form an image.
This process is essential for visual perception.
What does a green filter do?
A green filter absorbs all colours except green, and transmits green.
This property is used in various optical applications.
Why do red objects look red?
Because they reflect red light and absorb other colours.
This is due to the selective reflection of wavelengths.
What affects the pitch of a sound?
Frequency
Higher frequency → higher pitch.
This relationship is crucial in music and acoustics.
What affects the loudness of a sound?
Amplitude
Bigger amplitude → louder sound.
Loudness is perceived differently based on amplitude levels.
What is a longitudinal wave?
A wave where the oscillations are parallel to the direction the wave travels.
Sound waves are the most common example of longitudinal waves.
Example of a longitudinal wave
Sound waves.
These waves compress and rarefy the medium through which they travel.
Why is there no sound in a vacuum?
Sound needs particles to travel, and a vacuum has no particles.
This principle explains why sound cannot propagate in space.
What is the law of reflection?
Angle of incidence = angle of reflection.
This law applies to all reflective surfaces.
How fast does light travel?
About 300,000,000 m/s (3 × 10⁸ m/s).
This speed is a fundamental constant in physics.
How fast does sound travel in air?
About 343 m/s (depends slightly on temperature).
Sound speed varies with medium and temperature.
What is the human auditory range?
20 Hz to 20,000 Hz (20 kHz).
This range defines the frequencies humans can typically hear.
Why can’t humans hear ultrasounds?
Ultrasounds have a higher frequency than 20,000 Hz.
This limitation is due to the structure of the human ear.
How does a pinhole camera work?
Light travels in straight lines through a tiny hole. An inverted image forms on the screen inside.
This principle is based on the behavior of light.
What is dispersion?
The splitting of white light into colours (spectrum).
Example: a prism forming a rainbow.
How do you measure the speed of sound with two blocks of wood?
Stand far away from a friend. One person bangs blocks together. Time the delay between seeing the bang and hearing it. Use: Speed = distance ÷ time.
This method provides a practical way to calculate sound speed.
