Olympiad Test: Some Natural Phenomena - Class 8 MCQ

Resins that produce sparks include:

• Gum: This type of resin can ignite and create sparks when burned, making it useful in certain applications.

• Amber: Known for its fossilized tree resin, amber can also produce sparks under specific conditions.

• Both gum and amber are effective in creating sparks, each with unique properties.

Like charges have a specific interaction based on their nature:

• Repulsion: Charges that are alike, such as two positive or two negative charges, will push each other away.
• Attraction: This does not occur between like charges; they do not pull towards each other.
• No interaction: This is also not applicable, as like charges always repel.

In summary, when two objects carry the same type of charge, they will always experience a repulsive force that causes them to move apart.

The shaking of the earth is commonly referred to as an earthquake.

Key points about earthquakes:

• An earthquake occurs when there is a sudden release of energy in the Earth's crust.
• This release creates seismic waves, which are felt as shaking or vibrations.
• Earthquakes can vary in magnitude, affecting the intensity of the shaking.
• They can lead to significant damage, including destruction of buildings and infrastructure.
• Understanding earthquakes is crucial for preparedness and safety in affected areas.

Lightning occurs due to the sudden release of energy in the atmosphere. This process is known as electric discharge. Here are key points about lightning:

• It happens when there is a build-up of static electricity in clouds.
• The discharge can occur between clouds or from clouds to the ground.
• Lightning can result in a bright flash and a loud thunder sound.
• It is commonly associated with thunderstorms.

Other weather phenomena, such as rain, wind, or sun, do not cause lightning directly. Understanding the nature of lightning helps in appreciating its role in the atmosphere.

The interaction of charges is a fundamental concept in physics, often observed in various natural phenomena. Here are some key points to understand this concept better:

• Electrical discharge occurs when there is a sudden flow of electric current between two charged objects.
• This phenomenon can be seen in lightning, which is a large-scale electrical discharge that occurs during storms.
• Earthing is a safety measure that helps prevent electrical shock by directing excess charge safely into the ground.
• Unlike earthquakes, which are caused by tectonic movements, the interaction of charges specifically relates to electrical energy.

Understanding these interactions is crucial as they play a significant role in both natural events and technological applications.

Sparks can be seen on an electric pole when wires become

• Loose: When wires are not tightly secured, they can move and create friction, leading to sparks.

• Tight: Wires that are overly tight may not generate sparks, but can cause other issues such as breakage.

• Wrinkle: Wires that are wrinkled may also cause contact problems, but this is less common than looseness.

• None: Sparks should not occur if the wires are maintained properly.

In summary, the most likely cause of sparks on an electric pole is when the wires are loose.

Benjamin Franklin demonstrated the connection between lightning and electricity in 1752.

This pivotal experiment involved several key elements:

• Kite Experiment: Franklin flew a kite during a storm, using a metal key attached to the string to collect electrical charge.
• Proof of Electricity: The experiment provided evidence that lightning is a form of electricity.
• Lightning Rod: Following his findings, Franklin invented the lightning rod to protect buildings from lightning strikes.

This experiment was significant in the study of electricity and laid the groundwork for future developments in electrical science.

The charge acquired by a glass rod rubbed with silk is

• The glass rod becomes positively charged when rubbed with silk.
• This occurs due to the transfer of electrons from the glass rod to the silk.
• As a result, the rod ends up with a deficit of electrons, giving it a positive charge.

In summary, when a glass rod is rubbed with silk, it acquires a positive charge.

Lightning occurs when two charges interact.

For lightning to happen:

• One charge must be positive.
• The other charge must be negative.

When these opposite charges come together, they create a powerful electrical discharge, resulting in lightning. Charges that are both positive or both negative do not produce lightning, as like charges repel each other. Thus, the combination of one positive and one negative charge is essential for the formation of lightning.

Lightning conductors are essential safety devices designed to protect buildings from the damaging effects of lightning strikes.

• They provide a safe path for electrical discharge, directing it away from the structure.
• This helps to prevent fires and structural damage caused by lightning.
• Without a lightning conductor, a building is at a higher risk of being struck and sustaining severe damage.
• They are particularly important for tall buildings, which are more likely to be struck by lightning.

In summary, lightning conductors are crucial for safeguarding buildings against lightning-related hazards.

We cannot predict cyclones.

Cyclones, also known as hurricanes or typhoons, are complex natural phenomena influenced by various factors. Here are key points regarding their predictability:

• While meteorologists can forecast the likelihood of a cyclone forming, predicting their exact path and intensity remains challenging.
• Cyclone development depends on ocean temperatures, atmospheric conditions, and wind patterns, all of which can change rapidly.
• Advanced technology, such as satellites and computer models, helps in monitoring and making short-term predictions.
• However, long-term forecasts are still uncertain, and unexpected changes can occur.

In summary, while we can provide warnings about potential cyclones, their precise behaviour cannot be predicted with complete accuracy.

We cannot predict earthquakes.

The statement is accurate. Here are some key points:

• Earthquakes are natural phenomena that occur unexpectedly.
• Scientists can identify areas at higher risk but cannot forecast the exact timing or location.
• Research focuses on understanding patterns and improving safety measures.
• Preparedness is crucial in regions prone to seismic activity.

In summary, while we can study seismic zones, the precise prediction of when an earthquake will happen remains beyond our capabilities.

Wired telephones can be used safely during lightning storms.

• Using a wired phone during a lightning storm is generally considered safe.
• The risk of lightning strikes is primarily associated with cellular phones and other wireless devices.
• However, it is still advisable to take certain precautions:
• Avoid using the phone during severe storms.
• Ensure that your telephone lines are properly grounded.
• In summary, while wired phones are safer than wireless ones, caution is still recommended.

The Richter scale is a numerical scale used to measure the magnitude of earthquakes. It quantifies the amount of energy released during an earthquake.

• The scale typically ranges from 0 to 10.
• Each whole number increase on the Richter scale represents a tenfold increase in measured amplitude and approximately 31.6 times more energy release.
• For example, a 5.0 magnitude quake is ten times larger in amplitude than a 4.0 quake.
• It is primarily used for local earthquakes.

While the Richter scale is still commonly referenced, it has been largely replaced by the moment magnitude scale (Mw) for measuring larger quakes, which provides more accurate readings.

Building heavy houses in a danger zone is unwise.

• Heavy houses are more vulnerable to natural disasters.
• In areas prone to earthquakes, for example, heavy structures can lead to greater risks.
• Such buildings may pose a danger to occupants and nearby properties.
• Building lightweight, flexible structures is often safer in these zones.
• Local regulations usually discourage construction in high-risk areas.

Considering these factors, constructing heavy houses in a danger zone is not advisable.

Lightning strikes can cause significant damage to both life and property. Here are some key points to consider:

• Destruction of property: Lightning can ignite fires, damage electrical systems, and destroy buildings.
• Risk to life: Individuals struck by lightning may suffer severe injuries or even death.
• Natural occurrence: Lightning is a natural phenomenon that occurs during thunderstorms.
• Safety measures: It is crucial to follow safety guidelines during storms to reduce risks.

In summary, lightning strikes pose serious threats to both lives and structures.

Like charges attract each other.

This statement is false. In fact, like charges repel each other, while opposite charges attract.

• Like Charges: Charges that are the same, either both positive or both negative, will push away from each other.
• Opposite Charges: A positive charge and a negative charge will pull towards each other.
• This principle is fundamental in understanding how electric forces work.

The electric charges produced by rubbing are called static charges.

This statement is true because:

• Rubbing two objects together can transfer electrons.
• This transfer creates an imbalance of electric charge.
• The result is known as static electricity, which is a type of static charge.
• Static charges can cause objects to attract or repel each other.

In summary, when materials are rubbed against each other, they generate static charges.

The outermost layer of the Earth is not a single, unbroken surface.

It is divided into several large pieces, known as tectonic plates. These plates float on the semi-fluid layer beneath them and continuously move over geological time. Here are some key points:

• The Earth's crust consists of multiple tectonic plates.
• These plates can collide, pull apart, or slide past each other.
• This movement leads to various geological activities, such as earthquakes and volcanic eruptions.
• The boundaries where these plates meet are particularly active.

In summary, the outer layer of the Earth is not in one piece; instead, it is made up of many interconnected plates that shape our planet's surface.

In ancient times, people did not understand the true causes of earthquakes.

During that era, knowledge of geological processes was limited. Here are some key points:

• Earthquakes were often attributed to supernatural forces or the anger of gods.
• Natural explanations, such as tectonic plate movements, were unknown.
• People relied on myths and folklore to explain seismic events.
• Scientific understanding of earthquakes began to develop only in the modern era.

Overall, the lack of knowledge about geology led to misconceptions about the causes of earthquakes.