8th Class Science Some Natural Phenomena Lightning Earthquake

        Lightning

Lightning is one of the most deadly natural phenomena known to man. The bright flash of light which we see in the clouds is called lightning. Lightning is an electric current. Within a cloud many small bits of ice bump into each other as they move around in the air. Due to these collisions electric charges are produced. The positive charges form at the top of the cloud and the negative charges form at the bottom of the cloud. When the amount of these charges becomes extremely large, then the electric charges start flowing with high speed through air between them as a result an intense spark of electricity is produced in the sky.

          Earthquake

Earthquake is a destructive natural phenomenon which occurs due to sudden movements in earth7 crust. The shaking of the ground caused by sudden movements in earth's crust is known as earthquake. Earthquake sometimes causing great destruction. The intensity of an earthquake is measured by Richter scale. The place inside the earth's crust where the earthquake is generated is known as focus of the earthquake. The point on the earth's surface directly above the focus is called epicentre. The waves generated by an earthquake are called the seismic waves. The instrument which is used to measure and record the magnitude of an earthquake in terms of shockwaves is known as seismograph.

         What type of force is experienced between two like charged particles?

(a) Force of attraction

(b) Force of repulsion

(c) No force is experienced

(d) All of these

(e) None of these

Answer: (b)

          How many types of electric charges are there?

(a) One

(b) Two       

(c) Three

(d) Four

(e) None of these

Answer: (b)

• There are two types of electric charge; negative charge and positive charge
• Electrons carry negative charge whereas protons carry positive charge
• An electroscope is an instrument for detecting the presence of electric charge on an object
• The bright flash of light which we see in the clouds is called lightning.
• Earthquake occurs due to sudden movements in earth' crust..