Earthquake, Electric Charges & Earthing
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Practice Class 8 Science MCQ Questions with Answers based on NCERT concepts. Learn about earthquakes, magnitude, electric charges, attraction and repulsion of charges, charging by friction, and earthing with original explanations and exam-focused revision notes.
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Chapter Information
Subject: Science
Class: 8
Topics: Some Natural Phenomena & Electric Charges
Question Type: Multiple Choice Questions (MCQs)
Difficulty Level: Easy to Moderate
Based On: NCERT Concepts
Introduction
Natural phenomena such as earthquakes can cause sudden changes in the Earth’s surface, while electric charges produce interesting effects such as attraction, repulsion, and sparks. Understanding these concepts helps students connect classroom science with events observed in everyday life.
This practice set covers important concepts related to earthquakes, electric charges, charging by friction, and earthing in a simple and exam-oriented manner.
What You Will Learn
✔ Earthquakes
✔ Magnitude of earthquakes
✔ Richter scale
✔ Like and unlike electric charges
✔ Charging by friction
✔ Earthing
Why This Topic Is Important?
Earthquakes and electrical phenomena are important parts of everyday science. Understanding how earthquakes are measured and how electric charges behave helps students answer conceptual questions in school examinations and develop a better understanding of natural and physical phenomena.
Exam Relevance
These questions are useful for:
✔ CBSE Exams
✔ State Board Exams
✔ School Tests
✔ Unit Tests
✔ Half-Yearly Exams
✔ Annual Exams
✔ Olympiad Preparation
✔ Scholarship Examinations
Q1. The sudden shaking or trembling of the Earth is called?
A) Flood
B) Cyclone
C) Tsunami
D) Earthquake
Answer
Earthquake
Concept
An earthquake is a sudden movement or shaking of the Earth’s surface caused by movements within the Earth’s crust.
Explanation
The Earth’s outer layer is made up of large sections that can move relative to one another. Sudden movements beneath the surface can release energy, producing vibrations that travel through the Earth. These vibrations may cause the ground to shake.
Exam Focus
Remember: Sudden shaking of the Earth’s surface → Earthquake
Q2. Like charges, such as positive and positive, do what?
A) No effect
B) Attract each other
C) Repel each other
D) None of these
Answer
Repel each other
Concept
Electric charges interact with one another through electric forces.
Explanation
Two charges of the same kind push each other away. Thus, two positive charges repel each other, and two negative charges also repel each other.
On the other hand, unlike charges attract each other.
Exam Focus
Remember:
Like charges → Repel
Unlike charges → Attract
Q3. The power of an earthquake is expressed in terms of magnitude on a scale called?
A) Decibel scale
B) Richter scale
C) Celsius scale
D) Newton scale
Answer
Richter scale
Concept
The magnitude of an earthquake indicates the amount of energy associated with the earthquake.
Explanation
The Richter scale is a commonly taught scale used to express the magnitude of earthquakes. A greater magnitude indicates a stronger earthquake.
Exam Focus
Remember:
Earthquake magnitude → Richter scale
Q4. Which of the following can be charged easily by friction?
A) A plastic scale
B) An inflated balloon
C) Both A and B
D) A copper rod
Answer
Both A and B
Concept
Certain insulating materials can acquire electric charge when they are rubbed against another material. This process is called charging by friction.
Explanation
Both a plastic scale and an inflated balloon can be charged by rubbing them with suitable materials.
When two different materials are rubbed together, some electrons may transfer from one material to the other. As a result, the objects can acquire electric charges.
Therefore:
- Plastic scale → Can be charged by friction
- Inflated balloon → Can be charged by friction
Hence, the correct answer is:
Both A and B
Exam Focus
Remember: A plastic scale and an inflated balloon are common examples of objects that can be charged by friction.
Q5. The process of transferring charge from a charged object to the Earth is called?
A) Earthing
B) Sparking
C) Lighting
D) Charging
Answer
Earthing
Concept
The Earth can receive excess electric charge from a charged object.
Explanation
Earthing is the process in which excess electric charge is transferred from a charged body to the Earth. It is an important safety measure used in electrical systems to reduce the risk associated with unwanted electric charge.
Exam Focus
Remember: Transfer of excess charge to Earth → Earthing
Important Concepts
1. Earthquake
An earthquake is the sudden shaking of the Earth’s surface caused by movements and disturbances beneath the Earth’s crust.
2. Earthquake Magnitude
Magnitude represents the strength or size of an earthquake.
Important term:
Richter scale → Earthquake magnitude
3. Electric Charges
There are two types of electric charges:
- Positive charge
- Negative charge
Their basic interaction is:
$$
\text{Like charges} \rightarrow \text{Repel}
$$
$$
\text{Unlike charges} \rightarrow \text{Attract}
$$
4. Charging by Friction
When certain materials are rubbed together, electrons may transfer from one material to another.
Examples include:
- Rubbing a plastic scale with a suitable material.
- Rubbing an inflated balloon against hair or cloth.
5. Earthing
Earthing provides a path through which excess electric charge can flow safely into the Earth.
It is widely used as an electrical safety measure.
Related Practice Questions
- What causes the shaking of the Earth during an earthquake?
- What happens when two negative charges are brought close together?
- What is meant by charging by friction?
- Why is earthing important for electrical safety?
- What is the difference between like and unlike electric charges?
Mini Quiz Challenge
Fill in the blanks:
- Like charges ______ each other.
- Unlike charges ______ each other.
- The sudden shaking of the Earth is called an ______.
- The magnitude of an earthquake is commonly expressed using the ______ scale.
- The transfer of excess electric charge to the Earth is called ______.
Exam Tips
✔ Remember the difference between attraction and repulsion.
✔ Learn the relationship: Like → Repel, Unlike → Attract.
✔ Do not confuse the Richter scale with the decibel scale.
✔ Revise examples of charging by friction.
✔ Remember that earthing is related to the safe transfer of excess electric charge to Earth.
Quick Revision Notes
✔ Sudden shaking of Earth → Earthquake
✔ Earthquake magnitude → Richter scale
✔ Like charges → Repel
✔ Unlike charges → Attract
✔ Plastic objects and balloons can be charged by friction.
✔ Transfer of excess charge to Earth → Earthing
Common Mistakes Students Make
❌ Thinking like charges attract each other.
❌ Confusing Richter scale with Celsius or decibel scales.
❌ Assuming every material behaves in exactly the same way when rubbed.
❌ Confusing earthing with charging.
❌ Forgetting that electric charges can be positive or negative.
Key Takeaways
- Earthquakes cause sudden shaking of the Earth’s surface.
- Earthquake magnitude is commonly expressed using the Richter scale in school-level study.
- Like electric charges repel one another.
- Unlike electric charges attract one another.
- Some insulating objects can be charged through friction.
- Earthing transfers excess electric charge safely to the Earth.
FAQs
1. What is an earthquake?
An earthquake is the sudden shaking or trembling of the Earth’s surface caused by disturbances beneath the Earth’s crust.
2. What happens between two like charges?
Like charges repel each other.
3. What happens between unlike charges?
Unlike charges attract each other.
4. What is charging by friction?
It is the process in which an object becomes electrically charged through rubbing, generally because electrons are transferred between materials.
5. What is earthing?
Earthing is the process of transferring excess electric charge from a charged object to the Earth.
Conclusion
The concepts of earthquakes and electric charges help students understand both natural phenomena and everyday electrical effects. Knowing how earthquake magnitude is represented, how electric charges interact, how objects can become charged by friction, and how earthing provides electrical safety makes these topics easier to understand and remember.
NCERT Reference
Book: NCERT Science Class 8
Relevant NCERT Topics: Some Natural Phenomena and Electric Current and Its Effects
Based On: NCERT Concepts and Class 8 Science Curriculum
1. Good Conductor of Electricity – Copper
A good conductor is a material that allows electric current to pass through it easily.
Why copper is a good conductor:
- It has free electrons that move easily
- It offers very low resistance to electric current
Other materials:
- Rubber, plastic, and wood are insulators (they do not allow current to pass)
Example:
Copper wires are used in household wiring and electrical devices.
2. Distilled Water – Poor Conductor
Pure or distilled water is a poor conductor of electricity.
Reason:
- It does not contain free ions (charged particles)
- Electricity needs ions to flow through a liquid
Important point:
- Normal tap water conducts electricity because it contains dissolved salts and minerals
Example:
Distilled water is used in batteries to avoid unwanted conduction.
3. Electroplating (Deposition of Metal Layer)
Electroplating is the process of depositing a thin layer of one metal on another material using electricity.
How it works:
- Electric current is passed through a solution
- Metal ions get deposited on the object
Why it is used:
- To prevent rusting
- To improve appearance (shine)
- To increase durability
Examples:
- Gold plating on jewelry
- Chromium plating on taps and car parts
4. LED (Light Emitting Diode)
LED is an electronic device that emits light when electric current passes through it.
Full form: Light Emitting Diode
Features:
- Consumes very less energy
- Produces very little heat
- Long-lasting compared to bulbs
Uses:
- Indicator lights
- TVs, bulbs, and displays
5. Gas Formed at Anode – Oxygen
When electric current is passed through acidified water, it splits into gases.
Process: Electrolysis of water
At electrodes:
- Cathode (negative terminal) → Hydrogen gas
- Anode (positive terminal) → Oxygen gas
Reason:
Water (H₂O) breaks into hydrogen and oxygen during electrolysis.
Example:
Used in experiments to demonstrate decomposition of water.
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