P2 Flashcards
What is thermal conductivity?
Each rod has the same temperature difference between its ends. Each rod is the same length and diameter. The energy transfer by conduction through a material depends on THERMAL DECOMPOSITION.
Why does insulation matter?
Materials that are good insulators are necessary to keep you warm in winter, whether you are at home or outdoors. Good insulators need to be materials that have low thermal conductivity, so energy transfer through them is as low as possible.
What does energy transfer per second depend on?
The temperature difference across the material.
The thickness of the material.
The thermal conductivity of the material.
What is energy of the Sun?
When you are in sunlight, you are absorbing infrared radiation from the Sun, infrared radiation and visible light are parts of the electromagnetic spectrum. So too are radio waves, microwaves, ultraviolet rays and X-rays. Electromagnetic waves are electric and magnetic waves that travel through space. The wavelength of light increases across the visible spectrum from blue to red light. Infrared waves are longer in wavelength than visible light waves. The Sun emits all types of electromagnetic radiation. Fortunately, the Earth’s atmosphere blocks most of the types of radiation that are harmful to people. But it doesn’t block infrared radiation or light from the Sun.
What is radiation and surface temperature?
If you want to see animals and people in the dark, you need to use special cameras. These cameras detect INFRARED RADIATION.
THE HIGHER THE TEMPERATURE OF AN OBJECT, THE MORE INFRARED RADIATION IT EMITS IN A GIVEN TIME.
What is a perfect black body?
A perfect black body is an object that absorbs all the radiation that hits it. It doesn’t reflect any radiation, and it doesn’t transmit any radiation. A good Absorber is also a good emitter, so a perfect black body is also the best possible emitter, so a perfect black body is called BLACK BODY RADIATION. No other object emits or absorbs radiation as effectively asa black body.
What happens to an object that has a constant temperature?
IT EMITS RADIATION ACROSS A CONTINUOUS RANGE OF WAVELENGTHS.
What is absorption and emission of infrared radiation?
Every object absorbs and emits infrared radiation, whatever its temperature is. If an object has a constant temperature, the object emits infrared radiation at the same rate as it absorbs it. When an object absorbs radiation faster than it emits radiation, its temperature increases.
How is radiation and the Earth’s temperature?
Reflected back into space or absorbed by the Earth’s atmosphere or by the Earth’s surface.
Emitted from the Earth’s surface and from the Earth’s atmosphere into space.
How about gases in the atmosphere?
Water vapour, methane and carbon dioxide(greenhouse gases) absorb longer wavelength infrared radiation from the Earth and prevent it escaping into space. These gases absorb the radiation and emit it back to the surface. This process makes the Earth warmer than it would be if these gases were not in its atmosphere.
What does temperature rise depend on when a substance is heated?
The amount of energy supplied to it.
The mass of the substance.
What the substance is.
What is specific heat capacity?
Is the energy needed to raise the temperature of 1kg of the substance by 1°c.
What is the equation for specific heat capacity?
Energy transferred/mass x temperature change.
How do you reduce the rate of energy at home?
Houses are heated by electric or gas heaters, oil and gas central heating systems, or by solid fuel in stoves or in fireplaces. Whichever form of heating you have in your home, the heating bills can be expensive. When your home heating system is transferred energy into your home to keep you warm, energy is also transferring to the surroundings outside your home.
What are sonar panels?
Heating a home using electricity or gas can be expensive. Solar panels absorb infrared radiation from the Sun and are used to generate electricity directly(solar cell panels) or to heat water directly(solar heating panels). In the northern hemisphere, a solar panel is usually fitted on a roof that faces south so that it absorbs as much infrared radiation from the Sun as possible.
