physics year 9

What is convection?

Convection is the process of heat transfer through a fluid (liquid or gas) by the movement of the fluid itself.

How does convection create convection currents?

When a fluid is heated, it expands and becomes less dense, causing it to rise while cooler, denser fluid sinks to create a convection current.

What is an example of convection in day-to-day life?

Boiling water, where hot water at the bottom rises, and cooler water at the top sinks.

What is conduction?

Conduction is the process of heat transfer through a material by direct contact.

What mechanism underlies conduction?

Heat is transferred from hotter to cooler areas through the vibration and collision of particles.

What is an example of conduction?

Touching a metal spoon in hot soup; heat is conducted from the soup to the spoon.

What is the Doppler effect?

The change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source.

How does the Doppler effect occur?

When a source moves towards an observer, waves compress, increasing frequency; moving away stretches waves, lowering frequency.

What is an example of the Doppler effect?

The change in pitch of a siren as an ambulance passes by.

What is radiation?

Radiation is the process of heat transfer through electromagnetic waves which does not require a medium.

What is an example of radiation?

Heat from the sun reaching the Earth.

What is the Big Bang theory?

The prevailing cosmological model stating that the universe began in an extremely hot, dense state and has been expanding.

What key evidence supports the Big Bang theory?

The observed expansion of the universe, cosmic microwave background radiation, and the abundance of light elements.

What is Cosmic Microwave Background Radiation (CMBR)?

The afterglow of the Big Bang, representing the thermal radiation from the early universe.

What are the two main types of waves?

Mechanical waves that require a medium and electromagnetic waves that do not.

What is the wave equation?

The relationship between wave speed, frequency, and wavelength given by v = f λ.

What are the properties of waves?

Wavelength, frequency, amplitude, and speed.