Lakhmir Singh Solutions - Science - Class 8 solutions for Chapter 15 Some Natural Phenomena

What are the two kinds of electric charges?

What kind of electric charge is acquired:

(a) By a glass, rod rubbed with silk cloth?

(b) By a plastic comb rubbed with dry hair?

What type of electric charge is acquired by a rubber balloon when rubbed with a woollen cloth?

A negatively charged object attracts another charged object placed near it. What is the nature of a charge on the other object?

A positively charged object repels another charged object kept close to it. What is the nature of a charge on the other object?

A negatively charged object repels another charged object held near it. What is the nature of a charge on the other object?

An inflated rubber balloon and a woollen cloth are rubbed together. What type of charge is acquired by:

(a) Woollen cloth, and (b) rubber balloon?

Name the device to detect electric charge on a body.

When an object is touched with the metal top of an electroscope, its aluminium leaves diverge. What conclusion do you get from this observation?

What name is given to the flash of light which occurs in the sky during the rainy season?

Why should a person not stand under a tree during a thunderstorm?

Name the scientist who showed that lightning is electric.

Name the device which is used to protect a tall building from lightning.

What name is given to the phenomenon in which the earth shakes suddenly for a very short time?

Name one destructive natural phenomenon which cannot be predicted in advance.

List three states in India where earthquakes are more likely to occur.

Name the instrument used to measure and record an earthquake.

What was the magnitude of Bhuj and Kashmir earthquakes on the Richter Scale?

Name the scale on which the magnitude (or intensity) of an earthquake is expressed.

For what purpose is the Richter Scale used?

Name two events (other than earthquakes) which can cause tremors on the earth.

In the context of an earthquake, which one is deep under the ground: focus or epicentre?

State whether the following statements are true or false:

(a) Like charges attract each other.

(b) A charged glass rod attracts a charged plastic straw.

(c) A lightning conductor cannot protect a building from lightning.

(d) Earthquakes can be predicted in advance.

(e) An earthquake of magnitude 2 on the Richter Scale is ten times as strong as an earthquake of magnitude 1 on the same Scale.

(f) The plates of earth's crust are continuously moving.

(g) An earthquake is measured and recorded by using an instrument called an electrocardiograph.

Fill in the following blanks with suitable words:

(a) Like charges _________; unlike charges _________

(b) Rubbing glass with silk makes a _________ charge on the glass.

(c) Combing your hair makes a _________ charge on the comb.

(d) The negatively charged particles which are transferred from one object to another during charging by friction are called _________

(e) The charging of an object by rubbing it with another object is called charging by _________

(f) In an electroscope, the aluminum leaves diverge because like charges_

(g) _________ is provided in buildings to protect us from electric shocks due to any leakage of electric current.

(h) Lightning is nothing but an _________ spark.

(i) Each fragment of the earth's crust is called a _________

Why does a plastic comb rub with dry hair attract tiny pieces of paper?

How will you charge an inflated rubber balloon by the method of friction?

How will you charge a plastic comb (plastic scale or plastic pen) by the method of friction?

How will you charge a ballpoint pen refill by the method of friction?

What will you observe when the metal top of an electroscope is touched with a glass rod which has been rubbed with silk cloth? Give a reason for your answer.

What will you observe when the metal top of an electroscope is touched with a plastic comb rubbed in dry hair? Give the reason for your answer.

What happens when we touch the metal top of a charged electroscope with our finger? What is this process known as?

Explain why a charged body loses its charge when we touch it with our hand.

What happens when two moving plates of earth's crust collide head-on with each other?

What precautions would you take to protect yourself during an earthquake if you are outdoors?

State any two precautions which should be observed by people living in seismic zones for protection against earthquakes.

Which of the following cannot be charged by friction, if held by hand?

(a) A plastic scale.

(b) A copper rod.

(c) An inflated balloon.

(d) Woollen cloth.

When a glass rod is rubbed with a piece of silk cloth, then:

(a) The glass rod and silk cloth both acquire positive charge

(b) The glass rod becomes positively charged while the silk cloth has a negative charge.

(c) The glass rod and silk cloth both acquire a negative charge.

(d) The glass rod becomes negatively charged while the silk cloth has a positive charge.

Which of the following are transferred from one object to another when these objects are charged by friction?

(a) Atoms

(b) Protons

(c) Neutrons

(d) Electrons

The electric nature of lightning was established by a scientist named:

(a) Isaac Newton

(b) Robert Hooke

(c) Benjamin Franklin

(d) Thales

A plastic comb is rubbed with dry hair whereas a glass rod is rubbed with a piece of silk cloth. Which of these will get negatively charged?

A. Plastic comb B. Glass rod C. Dry hair D. Silk cloth

(a) A and B

(b) B and C

(c) A and D

(d) B and D

The magnitude of an earthquake is measured on:

(a) Celsius scale

(b) Kelvin scale

(c) Decibel scale

(d) Richter scale

An earthquake of magnitude 2 on the Richter scale is:

(a) Two lines as strong as an earthquake of magnitude 1

(b) Four lines as strong as an earthquake of magnitude 1

(c) Ten lines as strong as an earthquake of magnitude 1

(d) Hundred lines as strong as an earthquake of magnitude 1

The epicentre of an earthquake is:

(a) Deep under the crust of the earth

(b) In the mantle of the earth

(c) On the surface of the earth

(d) In the core of the earth.

The waves generated by the earthquake tremors are called:

(a) Ultrasonic waves

(b) Rhythmic waves

(c) Systemic waves

(d) Seismic waves

When an object gets negatively charged by the process of friction, then:

(a) The object loses some electrons

(b) The object loses some protons

(c) The object gains some electrons

(d) The object gains some Protons

The device used for detecting charge (positive or negative) on an object is called?

(a) Stethoscope

(b) Telescope

(c) Kaleidoscope

(d) Electroscope

A charged object attracts an uncharged object by producing opposite charges in the nearer end of the uncharged object by the process of:

(a) Electric potential

(b) Electric induction

(c) Friction

(d) Electromagnetic induction

A lightning conductor is a device which transfers:

(a) Electric energy

(b) Light energy

(c) Solar energy

(d) Photoelectric energy

When a plastic comb is rubbed with dry hair, the hair gets positively charged by friction. In this process:

(a) The hair loses some positive protons

(b) The hair gain some positive protons

(c) The hair loses some negative electrons

(d) The hair gains some negative electrons

Which of the following part of the earth is made up of molten iron?

(a) Mantle

(b) Inner-core

(c) Outer core

(d) Crust

Which of the following area of India is not the most threatened by an earthquake?

(a) North-east

(b) Kashmir

(c) West Bengal

(d) Rajasthan

The place inside the earth's crust where the earthquake is generated is called:

(a) Seismic zone of the earth

(b) The epicentre of the earthquake

(c) Fault zone of the earth

(d) The focus of the earthquake

An inflated rubber balloon is rubbed with a woollen cloth whereas a ballpoint pen refill is rubbed with a polythene bag. Which of these will get positively charged?

A. Inflated rubber balloon B. Woollen cloth C. Ballpoint pen refill D. Polythene bag

(a) A and B

(b) B and C

(c) A and D

(d) B and D

Lightning can even burn up a tree. Lightning contains a tremendous amount of:

(a) Heat energy

(b) Electric energy

(c) Chemical energy

(d) Nuclear energy

The tremendous electric charges in the atmosphere which produce sheet lightning in the clouds are produced by the process of:

(a) Friction

(b) Induction

(c) Conduction

(d) Convection

Lakhmir singh solutions science class 8 Solutions for Chapter 15 some natural phenomena