(Original post by TruthfulHoax)
First Question (Waves):
-Frequency alters pitch
-Reflected sound waves are echoes
-When waves are diffracted they spread out
-Most diffraction occurs when wavelength is the same as the object
-Longitudinal waves: Oscillations are parallel to direction of travel, waves transfer energy.
Electricity in a rural area:
-Expensive to lay cables/put infrastructure in place (cheaper to generate electricity independent of national grid)
Six Marker (HEP vs Wind):
-Wind more expensive
-Wind greater output
-HEP continuous output (more reliable)
-Neither release CO2
-HEP disrupts free movement of fish
-Wind is an eyesore
-Inefficient as some energy is wasted as light energy, some transferred to surroundings (not 100% goes to food in pan
-Fins: Surface area
-Colour: Black is good emitter and absorber of Infra-red radiation
-Same speed through a vacuum
-Not within visible spectrum (so are invisible to naked eye) ?
-Able to diffract/refract/reflect
-Use of Micro: Phones, Satellite Communications
-Use of Infra-red: Optical Fibres (for internet), Remote Controls (has appeared on mark schemes before)
-Cosmic Microwave Background Radiation
-Provides evidence for The Big Bang Theory/Big bang theory is only theory that can explain its presence
Solar Cell Question:
-Scientists strive for low cost because.. (according to table) cheaper to get two 10% efficient solar cells (1m2) than one 20% efficient solar cell - works out at a quarter of the cost to get two 10% (£10) compared to one 20% (£40)
Nuclear Power Advantages:
-Cheaper per kWh of electricity (table)
-No CO2 released ?
-Less fuel required for great amounts of energy so supply is not an issue ?
Nuclear Power Disadvantages:
-Produces radioactive waste (which must be disposed of properly to prevent harm)
-Fuel source (uranium/plutonium) is non-renewable
-High cost to decommission/Takes a long time to decommission
USB Heater - Factors:
-Surface area of mug in contact with heater
-Temp. difference between mug and heater ?
USB Heater - Conduction:
-Particles at base of mug gain energy, vibrate
-Pass on extra kinetic energy to neighbouring particles, carries on through the solid to transfer heat
Convection 4 marker:
-Heated particles gain (kinetic and thermal) energy
-Particles move apart
-That area of liquid becomes less dense, rises
How science works question:
-Thermometer has a smaller resolution (goes up in degrees while the data logger combo did 0.1 increments)
-Data logger continuously records information, not at intervals ?
-Removes human error
Why does the average temperature of a liquid go down as it evaporates?
-Particles gain energy when heated
-When heated enough particles rise up and leave the liquid, evaporating and taking energy with them
-As energy is no longer in the liquid the average particle energy decreases so the temperature also decreases