Class 8 Science

Natural Phenomena

Extra Questions

Short Answer Type Questions

Question 1: What do you understand by charging by rubbing? Give suitable examples.

Answer: Some objects get electrically charged when they are rubbed against one another. For example, plastic refill is rubbed with polythene both of them become charged.

Question 2: Explain the structure of lightning conductor.

Answer: This is a simple device which protects a building from being hit by lightning. It is composed of a vertical metallic rod which usually has a trident at the top. The base of the metallic rod is attached to thick metallic wire; which goes very deep inside the earth. This metallic wire provides a passage for earthing.

Question 3: How do tectonic plates create earthquake?

Answer: The tectonic plates are in continuous motion. They keep on brushing against each other or striking each other. When a tectonic plate brushes against another or strikes another tectonic plate; it results in vibrations in the tectonic plates. These vibrations are experienced by us in the form of an earthquake.

Question 4: Explain the structure of seismograph.

Answer: Seismograph is a device which records the seismic activities. It is composed of an oscillator, writing device and a roll of paper. The writing device is attached to the oscillator. In case of an earthquake, the oscillator begins to oscillate. This creates oscillation in the writing device; which plots wave-like patterns on the paper. The wave-like pattern is then analysed by seismologist to interpret the various features of an earthquake.

Question 5: When a comb is rubbed against hair, the comb attracts the bits of paper. Why?

Answer: When a comb is rubbed against hair, the comb attracts the bits of paper. This happens because the comb acquires a charge on rubbing.

Long Answer Type Questions

Question 1: Explain the working of electroscope.

Answer: When the brass disc of the electroscope is touched with a charged object, electric charge gets transferred to the gold leaf through the rod. This results in the gold leaves moving away from each other. This happens because both the leaves have similar charges.

Question 2: Explain the formation of lightning.

Answer: Formation of lightning takes place in following steps:

Question 3: Write some safety tips during lightning.

Answer: Safety during lightning:

Question 4: Suggest some tips for a quake safe building.

Answer: Following provisions make a quake safe building: