Imp Questions For All Chapters – General Science Class 7
Effects of Light
Short Questions
1. What is light?
→ Light is a form of energy that helps us see objects.
2. What is meant by the scattering of light?
→ The spreading of light in different directions when it hits small particles in the air is called scattering.
3. Why does the sky appear blue?
→ The air molecules scatter blue light more than other colors, making the sky look blue.
4. What is a shadow?
→ A shadow is a dark area formed when an object blocks the path of light.
5. What are the two types of shadows?
→ Umbra (dark shadow) and Penumbra (light shadow).
6. What is an umbra?
→ Umbra is the darkest part of a shadow where no light reaches.
7. What is a penumbra?
→ Penumbra is the lighter outer part of a shadow where some light reaches.
8. Why can’t we see shadows at noon on a zero shadow day?
→ At noon, the sun is directly overhead, so the shadow falls right below the object, making it almost invisible.
9. What is a solar eclipse?
→ A solar eclipse occurs when the moon comes between the sun and the earth, blocking sunlight.
10. What is a lunar eclipse?
→ A lunar eclipse occurs when the earth’s shadow falls on the moon, making it dark.
11. Why should we not watch a solar eclipse with bare eyes?
→ The sun’s rays can damage our eyes, so we need special eclipse glasses to view it safely.
12. What is the difference between a point source and an extended source of light?
→ A point source gives light from a single location, while an extended source spreads light over a larger area.
13. Why does space look dark?
→ Space has no air to scatter sunlight, so it appears black.
14. Why do we see different colors during sunrise and sunset?
→ Red and orange light scatter less, so they dominate at sunrise and sunset.
15. Why is light important in our daily life?
→ Light helps us see, grow plants, and generate electricity using solar panels.
Long Questions
1. What are the effects of the scattering of light?
→ Scattering of light makes the sky appear blue during the day and red or orange during sunrise and sunset. It also causes dust particles to become visible in a beam of sunlight.
2. What happens during a solar eclipse?
→ A solar eclipse occurs when the moon comes between the sun and the earth, blocking sunlight and creating temporary darkness in some areas.
3. What happens during a lunar eclipse?
→ A lunar eclipse occurs when the earth comes between the sun and the moon, causing the earth’s shadow to fall on the moon, making it appear dark or reddish.
4. Why does a bird flying high in the sky not cast a shadow on the ground?
→ The bird is too far from the ground, and its shadow spreads out and fades away before reaching the earth, making it invisible.
5. Why do we see the sun’s light even when it is below the horizon?
→ The earth’s atmosphere bends sunlight (refraction), allowing us to see the sun even before sunrise and after sunset.
6. How does light help us in our daily lives?
→ Light helps us see objects, grow plants through photosynthesis, and generate solar energy for electricity, making life possible on earth.
7. Why do astronauts see space as completely dark?
→ Space has no air to scatter sunlight, so even though the sun shines brightly, astronauts see complete darkness around them.
8. How can we safely observe an eclipse?
→ We can safely watch an eclipse using special eclipse glasses, a pinhole projector, or by watching a live broadcast, as direct viewing can damage the eyes.
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