Exam questions Flashcards
What properties do both infrared waves and microwaves have?
same speed or travel at the speed of light (in a vacuum) • transverse • transfer energy (from one place to another) • can be reflected • can be refracted • can be diffracted • can be absorbed / transmitted • can travel through a vacuum/space • can be polarised
Give two disadvantages of generating electricity using nuclear power stations.
non-renewable
produces radioactive / nuclear waste
long start-up time
Explain how the evaporation of a liquid causes the temperature of the remaining liquid to decrease.
particles with more energy
leave the (surface of the) liquid
(which) reduces the average (kinetic) energy (of the remaining particles)
What happens to the rate of evaporation when you use a smaller volume in the same beaker?
 no effect (as rate of evaporation is unchanged)
Give two factors, other than the material of the mug, that would affect the rate of energy transfer to the coffee.
surface area (of mug in contact with cup warmer) • thickness of mug • temperature of heater / coffee • power of the heater
Energy is conducted slowly through the base of the glass mug.
Explain how energy is conducted through the base of the glass mug
atoms (gain kinetic energy and) vibrate faster / more
energy is passed on from atom to atom by collision
Energy is transferred to the coffee at the bottom of the mug.
Explain how a convection current is set up in the coffee.
the particles spread out
(so) coffee becomes less dense
(so) the heated coffee rises
(and) cooler / denser coffee falls
What determines the pitch of a sound wave?
Frequency
State the name given to reflected sound waves.
Echoes
What is diffraction caused by?
The spreading out of sound waves
When does the most diffraction occur?
When the wave length is equal to the gap
Describe a longitudinal sound wave.
(a wave where the) oscillations are parallel to the direction of energy transfer
causing (areas of) compression and rarefaction
Use the kinetic theory to explain solids and gases
Solids
• (particles) close together
• (so) no room for particles to move closer (so hard to compress)
• vibrate about fixed point
• strong forces of attraction (at a distance)
• the forces become repulsive if the particles get closer
• particles strongly held together/not free to move around (shape is
fixed)
Gases
• (particles) far apart
• space between particles (so easy to compress)
move randomly
• negligible/no forces of attraction
• spread out in all directions (to fill the container)
What does a frequency of 440 Hz mean!?
440 waves in 1 secound
Describe how electricity is generated in a hydroelectric power station.
Water moves from a high to low area
transferring GPE to KE
rotating a turbine to turn a generator
transferring KE to electrical energy
