AQA Physics P1 Flashcards
Why do you place a lid on a thermal flask?
To reduce heat loss by convection as it stops hot particles escaping.
What is the purpose of a vacuum in a vacuum flask?
Reduce heat loss due to conduction and convection as both of these need particles, and the vacuum has no particles.
Why do I make part of a vacuum flask out of plastic?
To reduce heat loss due to conduction as plastic is a bad conductor.
Why do animals in cold climates have small ears?
To reduce heat loss due to radiation by reducing the surface area.
How best do you design a radiator, or something you want to keep cool?
Paint it black and increase the surface area
Why does painting something black increase heat loss?
Black is the best absorber and emitter of radiation.
How can I increase the surface area of a radiator?
Add fins
What is a U-Value?
A measure of how good or bad a material is at keeping in heat.
What does a big U-value mean?
It is a poor insulator.
What is specific heat capacity?
The energy needed to raise 1 kg of material by 1 degree.
The bigger the temperature difference…
The faster the object transfers heat to its surroundings.
How do I increase the rate of heat transfer from an object?
Increase the surface area, make the object out of a conductor.
How do I figure out if its worth it to use an LED light bulb?
Figure out how many normal light bulbs you would use in its life time and calculate how much they’d have cost by considering both the cost of the bulb and the cost of using the bulb.
What goes in the left hand side of a Sankey diagram?
The input energy.
What goes out the bottom of a Sankey diagram?
The waste energy.
What goes out the right hand side of a Sankey diagram?
The useful energy.
What does the width of the arrows mean in a Sankey diagram?
What proportion of the energy is transferred by that arrow.
What is pretty much always the waste energy?
Heat
What does waste energy do to the surroundings?
Usually heats it up.
What is the energy transfer in a light bulb?
Electric to Light, with waste heat
How do I calculate the amount of energy used by an appliance in kilowatt-hours?
Take the time in HOURS, take the power in KILOWATTS, multiply them together.
How does a fossil fuel power plant work?
Burn fossil fuels, use them to heat and boil water, use the steam to push a turbine around, use the turbine to rotate a generator, the generator produces power.
How does pumped storage hydroelectric power work?
Let water fall from a height to push a turbine around, use the turbine to rotate a generator, the generator produces power.
How does a nuclear power plant work?
Produce nuclear fission, the “waste” heat and boil water, use the steam to push a turbine around, use the turbine to rotate a generator, the generator produces power.
What are the advantages of renewables? (e.g. wind, tidal, geothermal)
They are renewable, they do not produce greenhouse gases.
What are the disadvantages of renewables? (e.g. wind, tidal, geothermal)
They are unreliable, and they need to be placed in a specific location (for example, wind turbines need to be placed somewhere windy)
What is geothermal energy?
Heat from hot rocks in the ground is used to boil water, turn a turbine, turn a generator and produce electricity.
What are the disadvantages of fossil fuels?
The produce greenhouse gases and contribute to global warming, they are not renewable.
What are the advantages of fossil fuels?
They have high energy density, they are reliable.
Why do we use step-up transformers in the National Grid?
Increase the voltage, to decrease the current, to reduce the heat loss, to increase the efficiency.
Why do we use step-down transformers in the National Grid?
To decrease the voltage, so its safe for consumers.
What does “decommisioning” a nuclear power plant mean?
Removing the radioactive waste materials safely.
What do waves do?
Transfer energy using vibrations.
What is a transverse wave?
A wave where the energy transfer is perpendicular to the direction of energy transfer.
What is a longitudinal wave?
A wave where the energy transfer is parallel to the direction of energy transfer.
Give an example of a transverse wave.
Any electromagnetic wave.
Give an example of a longitudinal wave.
Sound.
Give the electromagnetic spectrum, from low frequency to high frequency.
Radio, Micro, Infrared, Visible light, Ultraviolet, X-rays, Gamma Rays
Give the electromagnetic spectrum, from long wavelength to short wavelength.
Radio, Micro, Infrared, Visible light, Ultraviolet, X-rays, Gamma Rays
Give the electromagnetic spectrum, from high frequency to low frequency.
Gamma rays, X-rays, Ultraviolet, Visible light, Infrared, Micro, Radio
Give the electromagnetic spectrum, from short wavelength to long wavelength
Alts Gamma rays, X-rays, Ultraviolet, Visible light, Infrared, Micro, Radio
What is a danger of infrared?
Skin burns
What is a danger of microwaves?
Internal tissue heating
What are the dangers of ultraviolet?
Aging, sunBurns and Cancer
What are the dangers of visible?
Blindness
What are the dangers of X-rays?
Cell mutations and cancer
What are the dangers of gamma rays?
Cell mutations and cancer
What is an application of radio waves?
Broadcast communications
What is an application of micro waves?
Satellite communications (e.g. mobile phones)
What is an application of infrared?
Thermal imaging, normal cookery
What is an application of visible?
Photography
What is an application of ultraviolet?
Tanning salons, fraud prevention
What is an application of X-rays?
Producing shadowy images of bones for medical purposes.
What is an application of Gamma-rays?
Radiotherapy, detecting cracks inside metals.
Which region of the electromagnetic spectrum transfers heat?
Infrared
What is frequency?
The number of complete oscillations per second.
What is amplitude?
The distance from the equilibrium position to the peak of a wave.
What is wavelength?
The distance from the peak of a wave to the adjacent peak.
What is refraction?
When a wave changes direction when it moves from one material to another.
What is diffraction?
The spreading of a wave when it moves through a gap.
What is a normal?
A line at 90 degrees to the surface of a material.
What is a virtual image?
An image formed when imaginary rays cross.
What type of image is found in a mirror?
A virtual image.
What is the law of reflection?
The angle of incidence equals the angle of reflection
How do I hear a high amplitude sound wave?
Loud
How do I hear a low amplitude sound wave?
Quiet
How do I hear a high frequency sound wave?
High pitched
How do I hear a low frequency sound wave?
Low pitched
What is an echo?
A reflection of a sound
What name is given to the reflection of a sound?
An echo
What is redshift?
An increase in wavelength due to an object moving away.
What is blueshift?
A decrease in wavelength due to an object moving closer.
What is the Doppler effect?
A change in wavelength due to an object moving towards or away from the observer.
What does a high redshift galaxy indicate?
The galaxy is moving away quickly and is a long way away.
What does a blueshift indicate?
The galaxy is moving closer.
What does CMBR stand for?
Cosmic Microwave Background Radiation
How is redshift evidence for the big bang?
ALL galaxies are redshifted, so are moving away. The ones furthest away are most redshifted, so are moving fastest. This suggests everything started at a single point.
What are the two pieces of evidence for the big bang?
Redshift, the cosmic microwave background radiation.
What will happen to the cosmic microwave background in the future?
It will increase in wavelength and become radio waves.
What is the Big Bang Theory?
The UNIVERSE was created at a single point.
How does conduction happen in a metal?
Free electrons gain energy and move faster, they move throughout the metal, they collide with other particles in the metal and transfer energy to them.
Describe the process of convection.
Particles are heated and move faster. They spread out. This makes them less dense. Because the liquid or gas is less dense, it rises. Colder, more dense liquid or gas flows in to replace it. The process repeats.
How does evaporation cool down a liquid?
The fastest moving, most energetic particles escape, so the AVERAGE kinetic energy is lower, therefore the temperature of the liquid is lower.
How do I answer ANY question of heat transfer?
Heat loss due to conduction/convection/evaporation/radiation is increased/decreased due to .
Describe the particles in a solid. Close together, in a lattice, vibrating around fixed points.
Describe the particles in a gas. Far apart, free to move around, moving with rapid and random speeds.
