P2.1/2 - Energy From The Sun Flashcards
Energy from the Sun can be used to generate electricity directly. What do photocells do?
Photocells absorb light energy from the sun and transform it into electrical energy.
Cells (batteries) produce direct current. What type of current do photocells produce? Describe this current.
Photocells produce direct current (DC). A direct current is in the same direction all the time.
The amount of current a photocell produces depends on the ______ of solar cell that has light shining on it.
Area
Describe how a solar cell is a renewable energy source
Solar cells do not need much maintenance and there is no need for fuel to power them. They do not produce waste and have a long life. There is also no need for power cables so they can be used in remote locations to produce electricity to mobile phones etc.
How are photocells/solar cells used in space?
They are used on satellites to produce electricity.
State two disadvantages of using photocells to produce electricity
- You would need a very large area of photocells to generate the amount of electricity that is used by a small town.
- Photocells only work when the Sun is out and not in bad weather or at night.
How do photocells transform light into electrical energy?
When light shines on a photocell, energy is absorbed by the silicon atoms in the photocell. Electrons are knocked out of the silicon atoms and they are then free to flow, which creates a direct current.
The amount of electricity produced by a solar cell also depends on the ________ of the light shining on it and how far the solar cell is from the light source.
Intensity
How does passive solar heating work?
Buildings that use passive solar heating have large windows on the south side. Light energy passes through the windows and is absorbed by surfaces inside the building, heating them up.
What is a curved mirror used for?
A curved mirror is used to reflect light from the sun as another form of using energy from the sun,
How does a curved mirror work?
The curved mirror focuses the light energy from the sun onto one place. As a lot of energy is focused onto one place, it can get very hot.
What is a solar stove?
A solar stove is a way of using energy from the Sun to cook food. Light energy from a large area is reflected by curved mirrors on to a cooking pot.
How do the mirrors adjust to the movement of the sun throughout the day?
The mirrors or solar collectors have motors so that they can track the position of the Sun during the day and keep reflecting the light energy onto the same place.
In what form does the sun transfer energy to the Earth?
It transfers energy to the sun in the form of light and infrared radiation.
How can we get energy from the wind?
Winds are convection currents set up in the Earth’s atmosphere by energy from the Sun. The kinetic energy of the wind can be used to drive wind turbines directly.
