Some Natural Phenomena

Plastic comb gets electrically charged due to rubbing & therefore it attracts tiny pieces of paper which are neutral, as charged body can attracts an uncharged body.

Copper is a conducting object, as soon as it gets charged by rubbing with another material, the electric charge produced on its surface flow through our hand & body into the earth and it remains uncharged.

Three ways are:

1. Charging by rubbing: Charging of an object by rubbing it with another object is called charging by rubbing.The body which loses electrons acquires positive charge whereas the body which gains electrons acquires negative charge.
2. Charging by conduction: Charging a neutral body by bringing it in contact with a charged body is called charging by conduction.
3. Charging by induction: Charging a neutral body by bringing it near a charged body is called charging by induction

The process of transferring of charge from a charged object to the earth is called earthing. For our safety, most of the electrical appliances and the mains of the house are connected to earth, so that we can be prevented from getting an electric shock.

The following precautions should be taken are as follow:

1. Find a clear spot, away from buildings, trees, poles and electric poles, signboards and overhead power lines and drop to the ground
2. Do not use elevators if they are available at some place outside your house.
3. If you are in a car or a bus, do not come out and drive slowly to a clear spot.

The precautions that should be taken are as follow:

1. Take shelter under a table and stay there only, till the shaking stops
2. Stay away from the objects which are tall and heavy that may fall on you.
3. If you are on bed, do not get up and remain there only andprotect your head with pillow.

The process of transferring of charge from a charged object to the earth is called earthing. For our safety, most of the electrical appliances and the mains of the house are connected to earth, so that we can be prevented from getting an electric shock.

Lightning conductor is a device used to protect buildings from the damaging effects of lightning. It runs from the top to the bottom, along the outer wall of the buildings or any other object, which is to be protected. If lightning strikes the buildings or any other objects, then the lightning conductor provides an easy and direct path for the lightning bolt to pass to the ground without effecting them.

An electroscope is used to detect the charge on a body. A plastic comb is taken and it is rubbed on hair. Now, the plastic comb gets charged. The comb is touched with the electroscope plate. The static charges which are developed on the comb travels down the conducting wire and reach the two leaves of aluminium foil. Similar charges are acquired by both the leaves and as a result, they repel each other. Thus, the method of charging an uncharged body by bringing another charged body directly in contact is called charging by conduction. By this way, an electroscope can be charged through conduction.

As we know that electrical charges that are generated through friction are static, i.e they do not move by themselves and Motion of charges constitutes an electric current. When we take off our sweater there is a motion between the charges on the sweater and our body that produces electric current, which produces a crackling sound. Infact we can see a spark if we take off the sweater in the dark.

The earth's lithosphere is fragmented into many pieces. Each fragment is called a plate, also called tectonic plate. These plates are in continuous motion i.e. they float over hot magma.

Tremors or vibrations caused by the earthquakes which travel in the form of waves within the earth or along the earth's surface, are called seismic waves. Seismograph is an instrument which records these seismic waves.

After rubbing, ebonite rod acquires negative charge. Now when it is touched with the metal cap of an electroscope then both the metal cap & the leaves acquire negative charge due to conduction. Because of negative charge on both the leaves, divergence of leaves takes place. After rubbing with silk, glass rod acquire positive charge & when this positive rod is brought near the metal cap of the above negatively charged electroscope then due to induction positive charge gets induced in the leaves as a result collapsing of leaves takes place.

The leaves of an electroscope collapse as soon as we touch the metal cap with hand because the leaves of the charged electroscope lose charge to the earth through our body in other words leaves are discharged. This process is known as Earthing.

Nature of charge on the metal cap and on the leaves of the uncharged electroscope is negative.

Let the electroscope get charged with negative charge, by touching a negatively charged ebonite rod to the metal disc of the electroscope. The leaves of the electroscope open up (diverge).Now touch the body to be tested with the metal disc of the charged electroscope.

• If the divergence of the leaves increases, the body has similar charge that is the given body is also negatively charged.
• If the divergence of the leaves decreases, the body has unlike charge that is the given body is positively charged.

An electroscope can be used for following purposes:

1. To detect & measure the charge on a body.
2. To determine the nature of charge on a body.

Two places in India which are most threatened by earthquake are Kashmir and Rann of kutch.

The charged balloon has similar charges on its surfaces, since like charges repel each other thus charged balloon repels another charged balloon. When an uncharged balloon is brought near a charged balloon it acquires some opposite charge, since opposite charge attracts each other therefore a charged balloon attracts an uncharged balloon.

A charged body loses its charge if we touch it with our hand because the charges get transferred from our body to earth, this process is known as earthing.

The earth's lithosphere is fragmented into many pieces. Each fragment is called a plate, also called tectonic plate, these plates are in continual motion, when they brush past one another a plate goes under another because of collision, and they cause disturbance in earth’s crust, this disturbance shows up as an earthquake on the surface of earth.

If you are at home:

• Take shelter under the table and stay there until the stoppage of shaking
• Keep yourself away from the tall or heavy objects that may fall on you and damage you.
• If you are on bed, do not get up and keep a pillow on your head

If you are outside the home:

• Find a clear spot, away from buildings, trees, poles and electric poles, signboards and overhead power lines and drop to the ground.
• Do not use elevators if they are available at some place outside your house
• If you are in a car or a bus, do not come out and drive slowly to a clear spot.

During lightning avoid going at an open place, try to rush towards safe place like in a house or building, if you are travelling in nay vehicle like car or bus, you are safe inside with windows and doors of the vehicle closed. If you are in a forest take shelter under a smaller tree.

Lightning conductor is the device that protects a tall building from lightning strike, by providing an easier path for current to flow to earth than through the building. It consists of a thick copper strip of very low resistance connected to the ground below. A good connection to the ground is essential and is made by burying a large metal plate deep in the damp earth. In the event of a direct lightning strike, the current in the conductor may be great as to melt or even vaporize the metal, but the damage to the building will nevertheless be limited.

During lightning avoid going at an open place, try to rush towards safe place like in a house or building, if you are travelling in nay vehicle like car or bus, you are safe inside with windows and doors of the vehicle closed. If you are in a forest take shelter under a smaller tree.

During lightning avoid going at an open place, try to rush towards safe place like in a house or building, if you are travelling in nay vehicle like car or bus, you are safe inside with windows and doors of the vehicle closed. If you are in a forest take shelter under a smaller tree.

1. Lightning: Lightning is a natural phenomenon that has fascinated people for ages. Several people thought and researched about the cause of lightning and its process. Benjamin Franklin discovered for the first time that there is an electric discharge between clouds that produces a spark, and it is the electric spark between the clouds and the earth that appears as lightning. His famous kite experiment proved this fact. The occurrence of lightning is as follows. The formation of clouds involves friction between water particles in the atmosphere. The friction charges the particles. Among the positive and negative charges, the negative charge accumulates at the bottom of the cloud and the positive charges in its top. As the accumulation of the charge increases, the cloud will create a positive charge on the ground nearby. As the amount of charge increases, the negative charge on the cloud tends to make a path towards the ground, and it results in a narrow streak of electrical discharge, which we call lightning.
2. Earthing: The process of transferring of charge from a charged object to the earth is called as earthing. For our safety, most of the electrical appliances and the mains of the house are connected to earth, so that we can be prevented from getting an electric shock.

1. Richter scale: The Richter scale is used to rate the magnitude of an earthquake that is the amount of energy it released. This is calculated using information gathered by a seismograph.
2. Seismograph: Tremors or vibrations caused by the earthquakes which travel in the form of waves within the earth or along the earth's surface, are called seismic waves. Seismograph is an instrument which records these waves.