Particle Model & Heat
What does the particle model theory state about matter?
All things on Earth are made of particles and are in one of the three states of matter: solids, liquids, or gases
What is the difference between mechanical and electromagnetic waves?
Mechanical waves require a medium to travel through; electromagnetic waves can travel through a vacuum.
State the Law of Reflection.
The angle of incidence equals the angle of reflection.
What colours make up the visible spectrum?
Red, orange, yellow, green, blue, indigo, violet.
Define medium in terms of wave transfer.
A substance or material through which a wave travels.
What is the difference between heat and temperature?
Heat is the transfer of kinetic energy; temperature is a measure of the average kinetic energy of particles.
Name two examples of transverse waves and two examples of longitudinal waves.
Transverse examples – light waves, water waves; Longitudinal examples – sound waves, compression waves in a spring.
What is the difference between smooth and diffuse reflection? And give an example of each
Smooth reflection occurs on smooth surfaces and produces clear images; diffuse reflection occurs on rough surfaces and scatters light, producing no clear image. Smooth = mirror, diffuse = car body
Which type of EM wave has the longest wavelength?
Radio wave
What does it mean to justify a scientific answer?
Provide reasons and evidence to support your answer.
Name the three main methods of heat transfer.
Conduction, convection and radiation.
In sound waves, what is the name for areas where particles are close together and where they are far apart?
Compressions (close together) and rarefactions (spread apart).
Define refraction.
The bending of light as it passes from one medium to another due to a change in speed.
Give one beneficial use and one risk of UV radiation.
Benefit – produces vitamin D, sterilises equipment; Risk – causes sunburn, skin cancer, eye damage.
What does the term refractive index refer to?
A measure of how much light slows down in a medium compared to in a vacuum.
Why is a metal spoon hotter than a wooden spoon when left in hot soup?
Metal is a good conductor, so it transfers heat quickly; wood is an insulator, so it transfers heat slowly.
Why does sound travel faster in water than in air?
Particles in water are closer together, so vibrations pass more quickly between them than in air.
Name two differences between concave and convex lenses.
Concave lenses curve inward and diverge light rays; convex lenses bulge outward and converge light rays.
Compare microwaves, short radio waves, and long radio waves by wavelength.
Microwaves ~3 cm wavelength; short radio waves ~30 cm; long radio waves 3 m to 3000 m.
Give one example each of a conductor and an insulator.
Conductor – copper; Insulator – rubber.
In terms of particles, explain convection currents in a pot of boiling water.
Heated particles gain energy, become less dense, and rise; cooler, denser particles sink, creating a convection current.
Describe the relationship between frequency and pitch.
Higher frequency = higher pitch; lower frequency = lower pitch.
Explain how short-sightedness would be corrected with lenses.
Short-sightedness is corrected with concave lenses, which diverge light so it focuses correctly on the retina.
Why can gamma rays be both dangerous and useful?
Dangerous because they can damage living tissue and DNA; useful for cancer treatment and sterilising equipment.
Explain how values and needs of society can influence scientific research.
Research priorities often reflect what society values or needs, such as renewable energy or medical treatments.