[Sci] Energy On The Move (Semester 2) Flashcards
Describe the transfer of heat energy by conduction.
Transfer of heat energy via conduction occurs when two objects are touching.
Describe the transfer of heat energy by convection.
Transfer of heat energy via convection occurs in fluids via convection currents, when hot fluids rise up while cold fluids sink down.
Describe the transfer of heat energy by radiation.
Transfer of heat energy via radiation occurs via electromagnetic radiation, and does not require a medium.
Define the term ‘thermal conductor’.
any material that conducts heat
Define the term ‘thermal insulator’.
a material of relatively low heat conductivity that shields a volume against loss of heat.
Provide two examples of conductors.
carbon, copper
Provide two examples of insulators
styrofoam, glass
What is sound energy?
a form of energy associated with the vibration / disturbance of matter
How is sound energy transferred?
Particle to particle collisions in the medium transmitting the sound wave.
What are the variations of pressures in sound waves called?
Compressions and rarefactions
Why do sound waves require a medium to propagate?
Sound waves occur when particles vibrate, so a medium is required which contains particles that can be vibrated to create the vibrations.
What is a compression?
The areas of air where the particles are forced together
What is a rarefaction?
The areas of air where the particles are spaced further apart.
Explain the difference between a compression and a rarefaction.
- Compression: areas of air where particles are forced together
- Rarefaction: areas of air where particles are spaced further apart
What is a sound wave?
a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
What’s an alternate name for a sound wave?
longitudinal wave
Why can sound waves also be called longitudinal waves?
the air particles vibrate parallel to the direction of travel of the wave.
Why can’t sound travel through empty space?
- Sound is defined as the vibration of matter.
- Empty space / vacuum contains no matter, therefore sound cannot occur.
What is a transverse wave?
A wave in which the medium vibrates at right angles to the direction of its propagation
What is an example of a transverse wave?
Light
What does EM field stand for?
Electromagnetic field
What kind of medium is an EM field?
Nonphysical
Why doesn’t light require a medium through which to travel?
- Light is an excitation of the EM field: an EM wave.
- The EM field permeates everything in space, and in its ground state always exists.
- The excitations of the field can thus propagate through matter and a vacuum.
What is the wave equation?
v = f × λ (lambda)
What can the wave equation be used for?
the speed, frequency or wavelength of a wave
In the wave equation, what does v stand for?
speed of the wave (m/s)
In the wave equation, what does f stand for?
frequency of the wave (Hz)
In the wave equation, what does λ stand for?
wavelength of the wave (m)
