Renewable energy sources include solar energy, wind energy, hydropower, biomass energy, geothermal energy, etc.
1. Solar energy
Solar energy is a renewable energy source that has played a huge role in human production and life for more than 5,000 years. The uses of solar energy have changed greatly over time, from heating to powering satellites in space. However, there is still a lack of highly energy-efficient and low-priced solar power generation equipment in homes and various buildings.
2. Wind energy
When people look at the sea, they will find many wind turbines on the sea level. While they may not be the most attractive, they are very efficient, and that's what wind energy does, because Europe and some regions have endless coastlines, so wind power is more common in those places. Wind turbines are like the air intake of a jet engine. When air enters, it first encounters a set of fixed blades, which direct the air into a set of rotating blades.
3. Hydropower generation
Hydropower generation uses water with potential energy from high places such as rivers and lakes to flow to low places, converts the potential energy contained in it into kinetic energy of the hydraulic turbine, and then uses The water turbine is the driving force that drives the generator to generate electrical energy. The height of the water, the weight of the water, and even the speed at which the water flows can be used to generate electricity. The large number of rivers and different types of water flow on Earth means that we can install hydroelectric power stations in large numbers.
4. Biomass energy
The application of biomass energy is becoming more and more common in daily life. Biodiesel can power cars, buses, and commercial vehicles; biomass generators can provide electricity for homes; and new biomass energy sources are being discovered every day.
5. Geothermal energy
Geothermal energy is natural thermal energy extracted from the earth's crust. This energy comes from the lava inside the earth and exists in the form of heat. It is what causes volcanic eruptions and earthquakes. energy. Because radioactive particles slowly decay, geothermal energy is a renewable energy source. And as long as the earth is still rotating, geothermal energy will always exist, and there is no need to worry about them running out.
What is the working principle of a generator?
The renewable energy sources are as follows:
1. Solar power generation
Solar energy is a renewable energy source. For more than five thousand years, it has played a huge role in human production and life. The uses of solar energy have changed greatly over time, from heating to powering satellites in space.
However, there is still a lack of energy-efficient and low-cost solar power generation equipment in homes and various buildings.
The way a solar panel works is very simple, it is a panel made up of millions of solar cells. When the sun shines on these panels, the solar radiation energy is directly absorbed through the photoelectric effect or photochemical effect.Or indirectly converted into electrical energy.
This energy can power homes and is very cheap.
2. Wind power generation
When people look at the sea, they will find that there are many wind turbines on the sea level. While they may not be the most attractive, they are very efficient. Because Europe and some regions have endless coastlines, wind power is more common in these places.
Wind turbines are like the air intake of a jet engine. When air enters, it first encounters a set of fixed blades, which direct the air into a set of rotating blades.
The air pushes against the blades and emerges on the other side, where it flows more slowly than outside the turbine. The screen is shaped so that it directs relatively fast-moving air outside into the area behind the rotor.
Fast-moving air accelerates slower-moving air, causing the area behind the turbine blades to become low-pressure to draw more air past them.
3. Hydropower generation
Hydropower generation uses water with potential energy from high places such as rivers and lakes to flow to low places, converts the potential energy contained in it into kinetic energy of the hydraulic turbine, and then uses The water turbine is the driving force that drives the generator to generate electrical energy. The height of the water, the weight of the water, and even the speed at which the water flows can be used to generate electricity.
The large number of rivers and different types of water flow on Earth means that we can install hydroelectric power stations in large numbers.
4. Biomass energy
The application of biomass energy is becoming more and more common in daily life. Biodiesel can power cars, buses, and commercial vehicles; biomass generators can provide electricity for homes; and new biomass energy sources are being discovered every day.
5. Geothermal energy
Geothermal energy is natural thermal energy extracted from the earth's crust. This energy comes from the lava inside the earth and exists in the form of heat. It is what causes volcanic eruptions and earthquakes. energy.
Geothermal energy is a renewable energy source because radioactive particles slowly decay. And as long as the earth is still rotating, geothermal energy will always exist, and there is no need to worry about them running out.
Small science experiments suitable for junior high school students
1. A machine that converts mechanical energy into DC electrical energy.
2. It is mainly used as a DC motor required for DC motors, electrolysis, electroplating, electric smelting, charging and excitation of alternator. Although power rectifier components are used to convert alternating current into direct current where direct current is needed, DC motors cannot be compared with alternating current generators in terms of ease of use, operational reliability and certain working performance.
1. Working principle
The working model of the DC motor when the generator is running is as shown in the figure. The brushes A and B in the figure are connected to a DC load externally, and the motor is connected by a The prime mover drags to rotate in a counterclockwise direction. At the moment shown in the figure, the direction of the induced potential on component side ab is from end b to end a.The direction of the induced electric potential of cd is from end d to end c. The direction of the current ia in the element is brush B → d → c → b → a → brush A. The sides ab and cd of the element generate electromagnetic force f, which acts on the tangent of the armature circumference. The electromagnetic force f in the direction will produce an electromagnetic torque Tem, and the direction is clockwise, opposite to the direction of motor rotation. After turning 180 degrees, the direction of the current ia in the element is from brush B → a → b → c → d → brush A. The direction of the current I in the external circuit remains unchanged, and the direction of the generated electromagnetic torque Tem remains. is clockwise.
2. Working model
It can be seen from the above analysis that the DC motor has the following characteristics when running as a generator:
(1) In each case The current ia flowing in an armature coil is AC, and the induced electromotive force e generated at the same time is also AC.
(2) There is a DC potential between the brushes, and the induced electromotive force e and the current ia in the element have the same direction.
(3) The magnetic field generated by the armature current is also fixed in space.
(4) n is in the opposite direction to the electromagnetic torque Tem, and the electromagnetic torque Tem acts as a brake.
Batterys, rotating coils, small wind turbines, electric ships, and automatic flower watering devices shuttle in the track.
These five small inventions are relatively simple, and they all apply the physics knowledge learned in junior high school. It is very suitable for junior high school students with hands-on ability to make. Let’s explain how to make these three small inventions.
1. Batteries traveling in orbit
First of all, the tools we need to prepare are batteries, magnets and copper coils. Attach small magnets of the same polarity (both N or S) to the positive and negative terminals of the battery. Then put the prepared battery into the copper coil. At this time, you will find that the battery keeps shuttling in the copper coil.
Small magnets are the key point of this experiment. They not only generate a magnetic field, but also act as conductors, connecting the copper coil with the positive and negative poles of the battery. Even if a current is generated in the copper coil, at this time An energized copper coil generates a magnetic field according to the laws of electromagnetic induction and the right-hand rule.
2. Electric Small Boat
In this invention, we need to prepare batteries, motors, windmills, mineral water bottles, small wood chips, wires and tape. Cut the mineral water bottle horizontally, then put a small piece of wood in the middle of the mineral water bottle that has been divided into two, and fix it with tape. Then install the windmill and motor together, then fix the motor to the small wood piece and stick it with tape. The direction of the windmill is towards the stern of the boat (the tail of the mineral water bottle).
Then use wires to connect the battery and the motor. At this time, the motor drives the windmill, and the windmill generates wind energy, and the boat will move forward when placed in the water.
3. Automatic flower watering device
Automatic flower watering deviceThe principle is very simple, it uses the principle of atmospheric pressure. First we need to prepare a water bottle, and then two straws. Punch two holes in the water bottle, just big enough to insert a straw.
Then cut the straw to an appropriate length, insert the straw into the water bottle with the hole drilled, and then place the straw close to the water storage tray at the bottom of the flowerpot. When the water level in the water storage tray drops to the one of the two straws used as the air inlet, the other straw will suck out the water from the water bottle and water the flowers automatically.