AP 8th Class Physics 9th Lesson Questions and Answers Some Natural Phenomena

AP State Board new syllabus 8th Class Physics Guide 9th Lesson Some Natural Phenomena Textbook Exercise Questions and Answers.

AP 8th Class Physical Science 9th Lesson Questions and Answers Some Natural Phenomena

8th Class Physics 9th Lesson Some Natural Phenomena Questions and Answers (Exercise)

Select the correct option in Questions 1 and 2.

Question 1.
Which of the following cannot be charged easily by friction?
a) A plastic scale
b) A copper rod
c) An inflated balloon
d) A woollen cloth
Answer:
b) A copper rod

Question 2.
When a glass rod is rubbed with a piece of silk cloth the rod
a) and the cloth both acquire a positive charge.
b) becomes positively charged while the cloth has a negative charge.
c) and the cloth both acquire a negative charge.
d) becomes negatively charged while the cloth has a positive charge.
Answer:
b) becomes positively charged while the cloth has a negative charge.

Question 3.
Write T against true and F against false in the following statements.
a) Like charges attract each other (T/F)
Answer: False

b) A charged glass rod attracts a charged plastic straw (T/F)
Answer: True

c) Lightning conductor cannot protect a building from lightning (T/F)
Answer: False

d) Earthquakes can be predicted in advance (T/F)
Answer: False

Question 4.
Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.
Answer:
A charge is formed on the sweater when it is rubbed with the body of us. While taking off discharge takes place through the air between the body and the sweater and produces a crackling sound.

Question 5.
Explain why a charged body loses its charge if we touch it with our hand.
Answer:
A charged body loses its charge if we touch it with our hand because the charge passes to the earth through our body.

Question 6.
Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?
Answer:

• The destructive energy of an earthquake is measured on the Richter scale.
• Yes, a seismograph can measure an earthquake of magnitude 3 on the Richter scale.
• An earthquake of magnitude 3 won’t cause any damage.
• Sometimes it won’t be even felt.

Question 7.
Suggest three measures to protect ourselves from lightning.
Answer:

• Don’t stand under the long trees or high objects.
• Bathing should be avoided during thunderstorms to avoid contact with running water.
• During a thunderstorm contact with telephone cords, electrical wires and metal pipes should be avoided.

Question 8.
Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
Answer:

• Both the charged balloons possess the same kind of charges. We know that like charges repel each other. So, a charged balloon is repelled by another charged balloon.
• But a charged body attracts another uncharged body. So, an uncharged balloon is attracted by arfother charged balloon.

Question 9.
Describe with the help of a diagram an instrument which can be used to detect a charged body. (Activity-4)
Answer:
A device that can be used to test whether an object is carrying a charge or not is known as an electroscope.
Description :

• Take an empty jam bottle.
• Take a piece of cardboard slightly bigger in size than the mouth of the bottle.
• Pierce a hole in it so that a metal paper clip can be inserted.
• Open out the paper clip as shown in Figure.
• Cut two strips of aluminium foil about 4cm × 1cm each.
• Hang them on the paper clip as shown.
• Insert the paper clip into the cardboard lid so that it is perpendicular to it.
• Charge a refill and touch it.
  
• They repel each other.
• The aluminium foil strips receive the same charge from the charged refill through the paper clip.
• The strips carrying similar charges repel each other and they become wide open.
• In this way this device can be used to test whether an object is carrying a charge or not. This device is known as an electroscope.

Question 10.
List three states in India where earthquakes are more likely to strike.
Answer:
The three states in India where earthquakes are more likely to strike are Kashmir, Gujarat, Rajasthan and Assam.

Question 11.
Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
Answer:

• If I were outside my home I will find a clear spot, away from buildings, trees and overhead power lines and drop to the ground.
• If I were in a car or a bus, do not come out and I will ask the driver to drive slowly to a clear spot.
• I will not come out till the tremors stop.

Question 12.
The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.
Answer:

• No. I will not carry an umbrella.
• Because the umbrella is a metallic object.
• It catches the lightning easily and the electric charge passes through it and the body to the earth.
• It causes severe electric shock to us.

Extended Learning – Activities and Projects

Question 1.
Open a water tap. Adjust the flow so that it forms a thin stream. Charge a refill. Bring it near the water stream. Observe what happens. Write a short report on the activity.
Answer:
Short Report :
Material required : An empty refill, water tap.

Procedure :

• Open the tap and adjust the flow so that it forms a thin stream.
• Rub the refill with your dry hair several times.
• Bring the rubbed refill nearer to the stream.

Observation : The stream bends towards refill.
Reason : The refill gets the positive charge on rubbing it.
When it brings nearer to the water due to attraction water bends towards the refill.

Question 2.
Make your own charge detector. Take a paper strip roughly 10 cm × 3cm. Give it a shape as shown in Fig. Balance it on a needle. Bring a charged body near it. Observe what happens. Write a brief report, explaining its working.
Answer:
Short Report :
Material required : A balloon, paper, needle, thermocol.

Procedure :

• Make the balancing paper as shown in the figure.
• Rub the balloon with your dry hair several times.
• Bring the rubbed balloon nearer to the paper.

Observation : The paper strips swings.
Reason : The balloon is charged on rubbing it.
When it brings nearer to the paper due to attraction it moves.

Question 3.
This activity should be performed at night. Go to a room where there is a fluorescent tube light. Charge a balloon. Switch off the tube light so that the room is completely dark. Bring the charged balloon near the tubelight. You should see a faint glow. Move the balloon along the length of the tube and observe how the glow changes.
Caution : Do not touch the metal parts of the tube or the wires connecting the tube with the mains.
Answer:
Do it yourself.
Reason : The tube light contains gas inside it. When the charged balloon moves from one side to another of the tube light the negative charges on the balloon cause glow in the tube light.

Question 4.
Find out if there is an organization in your area which provides relief to those suffering from natural disaster. Enquire about the type of help they render to the victims of earthquakes. Prepare a brief report on the problems of the earthquake victims.
Answer:
Report:
1. It is widely accepted that earthquake poses many challenges to human life.
2. Accordingly, the main categories were:

• Health problems and issues : So many victims suffer from injuries and some of them feel depressed.
• Economic problems and issues : So many victims lose their houses, valuable properties, belongings, and crops.
• Improper management of human and non-human resources : They are not treated well by the organizations due to a lack of funds.
• Incomplete social services: The victims get incomplete service from others.

3. According to the results, earthquake victims face many challenges. Earthquakes sometimes trigger tsunamis, landslides and occasionally volcanic activity. Earthquakes impact food security and agriculture based livelihoods through loss and injury of family members and the workforce. loss of crop yields and livestock.

4. Therefore, fundamental steps can be taken to reduce survivors’ problems by considering all aspects of their health, improving equal distribution of social assistance and services provided, and using local social capital in a better way.

8th Class PS 9th Lesson Questions and Answers (Lab Activities)

Activity – 1

Write an activity to show the electrical charge on an object.
(OR)
What will happen when a ball pen refill rub with a piece of polythene?
(OR)
How do you generate static electricity?
Answer:

• Take a used ballpen refill and rub it vigorously with a piece of polythene.
• Bring it close to small pieces of paper.
• Take care not to touch the rubbed end of the refill with your hand or with a metallic object.
• Repeat the activity with small pieces of the dry leaf, husk and mustard seeds.
• Record your observations.
• When a plastic refill is rubbed with polythene, it acquires a small electric charge.

Question 2.
Collect the objects and the materials listed in the Table. Try to charge each by rubbing with the materials mentioned in the Table. Record your findings. You can add more items to the Table.

Objects rubbed	Materials used for rubbing	Attracts/ does not Attract pieces of paper	Charged/ not charged
Refill	Polythene, woollen cloth
Balloon	Polythene, woollen cloth, dry hair
Eraser	Wool
Steel spoon	Polythene, woollen cloth

Answer:

Objects rubbed	Materials used for rubbing	Attracts/ does not Attract pieces of paper	Charged/ not charged
Refill	Polythene, woollen cloth	Attracts	Charged
Balloon	Polythene, woollen cloth, dry hair	Attracts	Charged
Eraser	Wool	Attracts	Charged
Steel spoon	Polythene, woollen cloth	Does not attract	Not charged
Comb	Dry hair	Attracts	Charged
Plastic chair	Polythene, woollen cloth	Attracts	Charged
Plastic scale	Dry hair	Attracts	Charged

Activity – 3

How do you prove that a) Like charges repel each other b) Unlike charges attract each other ?
(OR)
What happens if two charged objects made of a) different materials or b) file same material are brought close to each other ?
a)

• Inflate two balloons. Hang them in such a way that they do not touch each other.
• Rub both the balloons with a woollen cloth and release them.
• You can observe that a charged balloon repelled a charged balloon.
• Now let us repeat this activity with the used pen refills.
• Rub one refill with polythene.
• Place it carefully in a glass tumbler using the tumbler as a stand.
• Rub the other refill also with polythene.
• Bring it close to the charged refill.
• You can observe that a charged refill repelled a charged refill.
• In this activity we have brought close together the charged objects that were made of the same material. Let’s find out.

b)

• Rub a refill and place it gently in a glass tumbler as before.
• Bring an inflated charged balloon near the refill and observe.
• They repel each other.

Let’s summarise the observations :

• A charged balloon repelled a charged balloon.
• A charged refill repelled a charged refill
• But a charged balloon attracted a charged refill.

Activity – 5.

Ask your parents about the huge damage to life and property caused by these earthquakes. Collect a few pictures showing the damage caused by these earthquakes from newspapers and magazines of those days. Prepare a short report on the suffering of the people during and after the earthquakes.
Answer:
After the earthquake :
Call the fire service, medical and police persons.
Quickly clear the debris caused by the earthquake, by carefully observing whether any people under the debris.
Save the people who are trapped under the debris by supplying oxygen, food, etc., Evacuate the people from that place and save from the upcoming earthquakes.
Give announcement of tsunami to be caused by the earthquake if necessary.
Arrange shelter and food for the people.

During the earthquake :
Leave the buildings immediately.
Go to open place.
Don’t use lifts. Use steps to get down.

If you are trapped in the house :
Off the power supply.
If any crack sounds observed in the building go and stand at corners of the walls.
Try to give signals to the outside rescue team by whistling, tapping tables etc.

Activity – 6

Locating the tsunami affected areas in the map:
Take an outline map of the world. Locate the eastern coast and Andaman and Nicobar Islands in India. Mark other countries around the Indian Ocean which could have suffered damage.
Collect accounts of the devastation caused by the tsunami in India from your parents, or other elders in the family or in the neighbourhood.

Devastation due to tsunami :

• Loss of lives, families and friends.
• Loss of properties.
• Loss of jobs and living.
• Emotional challenge.
• Loss of livestock.
• Dramatic or drastic changes to a whole community’s routine living.
• Negative impact on the affected regions, economy.
• Negative impact to the affected region’s tourism.

To the environment :

• Alternation to seaside terrain.
• Minor deforestation in the area effected by the tsunami.
• Wild life casualities.
• The sea will be temporarily littered with debris after the tsunami.