Physics 9 Lesson 61: Power generation – thermal and hydroelectric power
1. Theoretical Summary
1.1. The role of electricity in life and production
Electricity is easily converted into other forms of energy.
- Electrical energy converted to mechanical energy
- Electricity converted to heat
- Electrical energy converted into light energy
- Electrical energy converted into chemical energy
– Electricity is easily transmitted over long distances (no need for transport vehicles, warehouses, containers…, no environmental pollution). Electricity is transmitted by wires.
In a thermal power plant, the energy of the burned fuel is converted into electricity.
The thermal energy of coal and gas heats water to turn it into steam. Steam turns the steam turbine. The steam turbine rotates the generator to generate electricity.
In the Hydropower plant, the potential energy of the water in the reservoir has been converted into kinetic energy and then into electricity
The energy of the stream turns the water turbine. The water turbine rotates to generate electricity to generate electricity.
1.4. How to identify generator types?
– Based on the initial form of energy converted into electricity:
Thermoelectricity: the energy of the burned fuel is converted into electricity.
Hydroelectricity: the potential energy of the water in the reservoir is converted into electricity.
2. Illustrated exercise
Question 1: The potential energy of an object of weight P raised to a height h equals the work done by the object when it falls to the ground: A = Ph. How much electrical energy can a 1m thick layer of water on the surface of a reservoir with an area of lkm2 and 200m above the turbine gate of a hydroelectric plant provide?
The water layer is 1km . wide2, 1m thick, with a height of 200m that can be generated when flowing into the turbine is: A = Ph = Vdh
⇒ A = (1000000.1). 10000.2000 = 2.10twelfthJ.
(where V is the volume, d is the specific gravity of the water).
That work is equal to the potential energy of the water layer, when entering the turbine, it will be converted into electricity.
Verse 2: Explain why in the dry season with little rain, the capacity of hydroelectric plants decreases.
When there is little rain, the water level in the reservoir decreases, the potential energy of the water decreases, so in the parts of the power plant, all parts of the power plant decrease, leading to a decrease in electricity.
3.1. Essay exercises
Question 1: How is the transmission of electricity from the power plant to the place of consumption done? What’s more convenient than transporting coal, oil, and gas?
Verse 2: In thermal power plants and hydroelectric plants, energy is converted in many stages, what is the final form of energy before being converted into electricity?
Question 3: In thermal power plants and hydroelectric power plants, there is a similar part, the turbine. So what does the turbine do?
Question 4: Why do hydroelectric plants have to build reservoirs in the high mountains?
3.2. Multiple choice exercises
Question 1: The outstanding advantages of hydroelectric power plants are:
A. avoid environmental pollution.
B. The factory construction is simple.
C. the investment is not large.
D. can work well in both rainy season and dry season.
Verse 2: The part in a hydroelectric power plant that converts water energy into electricity is:
A. coal furnace
Question 3: At the hydroelectric plant
A. Heat energy turns into mechanical energy, and then into electricity.
B. potential energy is converted into kinetic energy and then into electrical energy.
C. Light energy turns into electricity.
D. chemical energy turns into electricity.
Question 4: In a thermal power plant, the direct agent that rotates the turbine is:
Through this lesson, students will be familiar with the knowledge related to Power Generation- Thermal and Hydroelectricity along with related exercises in many levels from easy to difficult…, they need to understand. :
Understand the role of electricity in life and production of thermal power, hydroelectricity.
Know how to identify different types of generators.