Science Question Answer (2 Marks)

The electric charges generated by rubbing are static electric charges. These electric charges remain bound on the surface of the charged object. When a plastic comb is dry hair, it becomes negatively charged. The negatively charged comb induces a positive charge on the pieces of paper which are neutral in nature. As we know that the unlike charges attract each other, plastic comb attracts tiny pieces of paper.

The Richter scale is used to measure the magnitude (or intensity) of an earthquake. It measures the power of an earthquake. The destructive earthquakes have magnitudes higher than 7 on the Richter scale.

The electric charges generated by rubbing are static electric charges. These electric charges remain bound on the surface of the charged object. A glass rod can be charged by rubbing it with silk cloth. When a glass rod is rubbed with silk, some of the electrons from the glass atoms are transferred to silk. Due to the deficiency of electrons in the glass atoms, it becomes positively charged. Whereas the silk has acquired electrons, it becomes negatively charged.

Lightening conductor is a device which is used to protect a tall building from lightening. A metallic rod, taller than the building, is installed in the walls of the building during its construction.

Seismograph is the instrument which is used to measure and record an earthquake. The tremors produce waves on the surface of the earth. These are called seismic waves. These waves are recorded by the seismograph.

A ballpoint pen refill can be charged by rubbing it against the wool cloth. It becomes negatively charged. When we bring it close to bits of paper, the paper gets attracted to it. Paper is electrically neutral. The negative charge on the pen induces a positive charge on the paper bits which are close to it that causes the paper to fly and stick to the pen.

The rubber balloon becomes negatively charged when rubbed with a woolen cloth. The woolen cloth acquires a positive charge.

The outermost layer of the earth is fragmented. Each fragment is called a plate. These plates are in continual motion. When they brush past one another, or a plate goes under another due to collision they cause disturbance. This disturbance in the earth’s crust shows up as an earthquake on the surface of the earth.

When a glass rod is rubbed with a silk cloth, it acquires positive charge. When it is touched with the metal top of an electroscope, both the metal top and leaves acquires a positive charge due to conduction. As a result of the positive charge on both the leaves, the divergence of leaves takes place.

We can see tiny sparks of light and hear a crackling sound when we take off the woolen sweater or a polyester shirt. It happens because the sweater or a polyester shirt gets charged due to friction between the sweater and the body.

Hills are above the sea levels and are nearer to the sky. The clouds are closer to the hills as compared to the grounds. As a result, the lightening can strike much easily and frequently in hilly areas.

The outermost layer of the earth is fragmented. Each fragment is called a plate. These plates are in continual motion. When two plates collide head on, they push each other up and form mountains. The Himalayas and other great mountain ranges were created by this process.

A charged body loses its charge or gets discharged when we touch it with our hand. This process is called Earthing. The process of transfer of charge from a charged body to the earth is called Earthing.

Lightning strike could destroy life and property. Lightning conductors can protect buildings from the effects of lightning. Lightning strikes the tall buildings and can result in fire.

If the leaves of the electroscope diverge or open up when an object is touched, the body is charged. The extent of divergence or opening up of the leaves is a measure of the charge on the body. A body with higher charge will cause greater opening up of the leaves.

Lightening can result in electric shocks, damage to the buildings and fire. The electric discharge from the clouds can travel through the metal objects and can result into the electric discharge to the person carrying it.

If there is no shelter available, we must stay away from all trees, poles or other metal objects. We must not lie on the ground but we should squat low on the ground. Hands must be placed on the knees and the head should be between the hands. This position will make us the smallest target to be struck.

A metallic rod which is taller than the building is installed in the walls of the building during its construction. One end of the rod is kept out in the air and the other end is buried deep in the ground. The rod provides easy route for the transfer of electric charge to the ground.

The leaves of an electroscope will collapse when we touch the metal cap with our hand. This is because the leaves of the charged electroscope lose charge to the earth or gets discharged through our body. This process is called Earthing. The process of transfer of charge from a charged body to the earth is called Earthing.

The electric charges generated by rubbing are static electric charges. These electric charges remain bound on the surface of the charged object. A plastic comb can be charged by rubbing. The plastic comb will carry a negative charge.

After rubbing the glass rod with silk cloth, the glass rod becomes positively charged. The silk cloth becomes negatively charged.

Trees are usually the tallest objects around and have many pointy tips. The electric field is strong near the pointed tips. The current from a lightening may leave the tree and jump over to the person standing near the tree. The current will then follow from the body of the person on its way to the ground.

Lightening conductor is a device which is used to protect a tall building from lightening. Lightening conductor is made up of metal which is a good conductor of electricity.

The nature of charge on the other object will be positive. This is because like charges repel each other and unlike charges attract each other.

After rubbing the plastic comb, it acquires negative charge. When it is touched with the metal cap of an electroscope, both the metal cap and the leaves acquire negative charge due to conduction. As a result of negative charge on both the leaves, divergence of leaves takes place.

Benjamin Franklin is the scientist who showed that lightening is electric in nature. He discovered many things about lightening and was the first to show that a thunderstorm lets out electricity.

The states in India where earthquakes are most likely to occur are Kashmir, Western and Central Himalayas, the whole of North-East, Rann of Kutch, Rajasthan and the Indo Gangetic Plane.

The nature of charge on the other object is negative. This is because like charges repel each other and unlike charges attract each other.

The magnitude of Bhuj and Kashmir earthquakes on the Richter Scale were more than 7.5 The destructive earthquakes have magnitudes higher than 7 on the Richter scale.

Lightening is the name given to the flash of light which occurs in the sky during the rainy season. The process of electric discharge between clouds and the earth or between different clouds causes lightning.

The nature of charge on the other object will be positive. This is because like charges repel each other and unlike charges attract each other.

It is not safe to carry an umbrella during thunderstorm. Umbrellas are made up of metals. Thunderstorms are accompanied with lightening. The electric discharge from the clouds can travel through the metal rod of the umbrella. It can result into the electric discharge to the person carrying it. Hence, it might be dangerous to carry an umbrella during thunderstorm.

1. After rubbing the glass rod with silk cloth, the glass rod becomes positively charged. The silk cloth becomes negatively charged.
2. The plastic comb acquires negative charge when it is rubbed with dry hair.

Precautions for protection during an earthquake if we are outdoors:

• We must find a clear spot, away from the buildings, trees and overhead power lines. We must drop to the ground.
• While driving, we must remain inside the car or a bus. We must drive slowly to a clear spot. We must not come out of the car or a bus till the tremors stop.

Focus of an earthquake is located deep under the ground. Focus is the point inside the crust where the pressure is released. The point on the earth’s surface above the focus is called the epicenter.

The lightening conductor is made of metal rod with a sharp pointed edge on the top. They are made of conductive material such as copper and aluminium. Copper and its alloys are the most common materials used in lightening conductors.

A metallic rod, taller than the building, is installed in the walls of the building during its construction. The lower end of the rod is buried deep in the ground and the upper end is kept out in the air. The metallic rod transfers the electric charge to the ground.

Earthquake is the phenomenon in which the earth shakes suddenly for a very short time. It is caused by a disturbance deep inside the earth's crust.

Electroscope is the device which is used to detect charge on a body. It is used for detecting, measuring and finding the nature of a charge.

An inflated balloon can be charged by rubbing it against the woolen cloth.
Explanation: Upon rubbing, the wool loses electrons and it causes the electrons to move from the wool to the balloon’s surface. The rubbed part of the balloon now has a negative charge.

The tremors on the earth can be caused when a volcano erupts or when a meteor hits the earth. It can also be caused by an underground nuclear explosion.

Focus of an earthquake is located deep under the ground. Focus is the point inside the crust where the pressure is released. The point on the earth’s surface above the focus is called the epicenter.

Earthquake is the destructive natural phenomenon which cannot be predicted in advance. The earthquakes can cause floods, landslides and tsunamis. Most earthquakes are caused by the movement of earth's plates.