📖 Chapter 4 of 9 · Green Energy - Basic 1 · Class 5–6
Chapter 4: Power from Flowing Water
How does water make power?
Flowing or falling water is strong — strong enough to spin a machine called a turbine. When the water rushes past and turns the turbine, it makes electricity. This is clean power from water, with no smoke.
What is a dam?
A dam is a big wall built across a river. It holds back a lot of water, then lets it rush down through turbines to make power. India has many large dams that give clean electricity to millions of people.
Story Time — The Wall That Held a Lake
Tenzin · a valley in Himachal Pradesh
Tenzin lived in a mountain valley with a fast, cold river. One day his class visited a great dam — an enormous curved wall holding back so much water it had made a shining lake. “Why build such a huge wall?” Tenzin wondered.
“Watch what happens to the water,” their guide said. She showed them how the held-back water was let out through tunnels, rushing down with tremendous force onto the blades of hidden machines. “That rushing water spins the turbines, and the turbines make electricity.”
Tenzin felt the ground hum with the power of the falling water. “So the river itself makes our electricity?” “The river's flowing water does,” the guide said. “We simply guide it past the turbines. It makes clean power, with no smoke, day and night, as long as the water flows.”
“Day and night?” Tenzin asked, surprised. “Unlike the Sun, which sleeps at night,” the guide smiled, “the river keeps flowing all the time. So water power can work around the clock.”
On the bus home, Tenzin watched his familiar river with new respect. It was not just for splashing and fishing — it was a tireless worker, lighting homes all through the valley. “The river never stops helping us,” he said quietly.
Story Time — The Little Water Wheel
Meera · Kochi, Kerala
By a small stream near her home in Kerala, Meera built a tiny water wheel out of sticks and leaves for fun. When she set it in the flowing water, it spun round and round all by itself. “Look, it's spinning without me touching it!” she called to her grandfather.
“The flowing water is pushing it,” he said. “And do you know — that is exactly how we make power from rivers, only with very big, strong wheels called turbines.” Meera looked at her little spinning wheel and then imagined a giant one.
“So my toy is a tiny power machine?” she asked, delighted. “In a way, yes,” her grandfather laughed. “If you connected it to the right parts, that spinning could make a little electricity. Big turbines in rivers and dams make a very great deal.”
Meera let her wheel spin on, powered only by the stream. “The water does all the work,” she marvelled. “All we do is put the wheel in the right place,” her grandfather agreed. “That is the clever part.”
From that day, Meera saw every stream and river a little differently — not just as water, but as gentle, endless power, waiting for a wheel to turn. She kept her little water wheel spinning by the stream all summer long.
Solved Examples
Think first, then read the answer.
1. How does flowing water make power?
Show answer
Answer: It spins a machine called a turbine, and the spinning turbine makes electricity.
2. What is a dam?
Show answer
Answer: A big wall across a river that holds back water and lets it rush down through turbines to make power.
3. Is water power clean?
Show answer
Answer: Yes — it makes electricity with no smoke.
4. Why can water power work at night too?
Show answer
Answer: Because the river keeps flowing all the time, unlike the Sun which sets at night.
5. What did Meera's little water wheel show?
Show answer
Answer: That flowing water can spin a wheel by itself — the same idea as a big turbine.
Check Your Understanding
A. Fill in the blanks
- Flowing water can spin a _______.
- A big wall across a river is a _______.
- Water power makes no _______.
B. Yes or No
- Falling water can make electricity. ( ___ )
- A dam holds back water. ( ___ )
- Water power only works in the daytime. ( ___ )
C. Talk about it
- Have you seen a river or a dam? Describe it.
- Why is flowing water useful to us?
Check your understanding
Tap an answer to see if it is correct. This is just for fun — nothing is saved.
1. What can flowing water spin?
- A turbine
- A cloud
- A star
Show answer
A. A turbine
2. What is a dam?
- A wall across a river
- A kind of boat
- A bulb
Show answer
A. A wall across a river
3. Why can water power work at night?
- The river keeps flowing
- It uses the Moon
- It cannot
Show answer
A. The river keeps flowing