Question Answers For All Chapters – General Science Class 7
Static Electricity-Solutions
Exercise
1. Choose the correct option and fill in the blanks.
(always repulsion, always attraction, displacement of negative charge, displacement of positive charge, atom, molecule, steel, copper, plastic, inflated balloon, charged object, gold)
(a) There is always repulsion between like charges.
(b) Displacement of negative charge is responsible for generating electric charge in an object.
(c) A lightning conductor is made of a copper strip.
(d) Plastic does not get electrically charged easily by rubbing.
(e) There is always attraction when opposite electric charges come near each other.
(f) A charged object can be detected with an electroscope.
2. Explain why it is not safe to go out with an umbrella when there is heavy rain, lightning, or thunder.
- An umbrella has a metal rod, which can attract lightning.
- Lightning can strike the metal, causing electric shock or severe injury.
3. Answer in your own words.
(a) How will you protect yourself from lightning?
- Stay indoors and away from open fields and trees.
- Avoid using metal objects, electrical appliances, and water during a thunderstorm.
(b) How are charges generated?
- When two objects are rubbed together, electrons transfer from one object to another.
- One object becomes positively charged, and the other becomes negatively charged.
(c) In the lightning conductor, what provision is made for spreading the electricity into the ground?
- A copper strip is connected to a cast iron plate, placed in a pit filled with coal and salt.
- This allows the electric charge to spread into the ground safely.
(d) Why do farmers stick an iron staff into the ground while working in the field in rainy conditions?
- The iron staff acts as a lightning conductor, directing lightning safely into the ground.
- This prevents injury to farmers and protects them from electric shock.
(e) Why is lightning not seen every day during the rainy season?
- Lightning occurs only when clouds rub against each other, creating an electric charge.
- Not all rainy days have the right conditions for lightning formation.
4. What are the characteristics of a static electric charge?
- Generated by friction (rubbing objects together).
- Does not flow, stays on the object.
- Opposite charges attract, like charges repel.
- Easily lost in moist air.
5. What is the damage caused by lightning? How will you create awareness to prevent it?
Damage caused by lightning:
- Fire and destruction of trees, houses, and buildings.
- Injury or death of humans and animals.
- Power failure and electronic damage.
How to create awareness:
- Educate people to stay indoors during storms.
- Promote the use of lightning conductors in buildings.
- Spread information through schools, posters, and social media.
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