Grade 7 Science: Hydroelectric Power as a Source of Electricity Lesson Notes

Topic: Hydroelectric Power and How Electrical Energy is Produced

Learning Objectives:

By the end of this lesson, students should be able to:

1. Define hydroelectric power.

2. Explain how hydroelectric power is generated.

3. Describe the process of converting water energy into electrical energy

Lesson Notes:

1. Introduction to Hydroelectric Power

Hydroelectric power is energy produced from moving water. It is one of the most widely used renewable sources of energy in the world. The term "hydroelectric" comes from "hydro," meaning water, and "electric," meaning electricity.

Key Terms:

Hydroelectric power: Electricity generated using the energy of moving water.

Renewable energy: Energy that comes from sources that can be replenished naturally, like water, wind, and sunlight.

Dam: A barrier constructed to hold back water and raise its level, forming a reservoir.

2. How Hydroelectric Power is Generated

The process of generating electricity from water involves several steps:

Step 1: Water is Stored in a Dam Dams are built on large rivers with a significant drop in height. The dam holds a large amount of water in a reservoir. The potential energy in the stored water is used for power generation.

Step 2: Water Flows Through the Penstock Water from the reservoir is released through a narrow channel called a penstock. The flow of water is directed towards the turbines.

Step 3: Turbines are Turned by Water The flowing water spins large blades in the turbine. The turbines are connected to generators.

Step 4: Generators Produce Electricity As the turbines spin, they power the generators. Inside the generator, mechanical energy is converted into electrical energy using electromagnetic induction.

Step 5: Electricity is Sent to Power Lines The electrical energy produced in the generator is transmitted through power lines to homes, schools, industries, and other places where it is needed.

3. Advantages of Hydroelectric Power

Hydroelectric power has several benefits:

It is a renewable and sustainable source of energy.

It doesn’t pollute the environment with harmful gases.

Once the dam is built, it is relatively cheap to produce electricity.

Dams can also control flooding and provide water for irrigation.

4. Disadvantages of Hydroelectric Power

Despite its benefits, hydroelectric power has some downsides:

Building dams can be expensive and may displace people and animals.

The natural flow of rivers is disrupted, which can affect ecosystems.

In areas with droughts or low rainfall, hydroelectric power may not be reliable.

Summary:

Hydroelectric power is a renewable form of energy produced by the movement of water. Water stored in dams flows through turbines, spinning them to generate electricity. This clean and efficient energy source is widely used around the world but requires careful planning to avoid environmental and social impacts.