Lakhmir Singh and Manjit Kaur Science solution: Some Natural Phenomena Chapter 15. Here you get easy solutions of Lakhmir Singh and Manjit Kaur Science solution Chapter 15 . Here we give Chapter 15 all solution of Class 8. Its help you to complete your homework.
- Board – CBSE
- Text Book – SCIENCE
- Class – 8
- Chapter – 15.
VERY SHORT ANSWER TYPE QUESTIONS :
(1.) Positive and negative.
(2.) a> Positive, b> Negative
4.) Positive charge.
5.) Positive charge.
6.) Negative charge.
7.) a> Negative, b> Positive.
8.) a> Positive, b> negative
10.) Object has electric charge on it.
12.) The light can hit in the tree.
13.) Benjamin Franklin.
14.) Lightning conductor.
17.) Kashmir, western and central Himalayas, the whole of North-East.
19.) 7.7 on richter scale.
20.) Richter scale.
21.) To watch The magnitude of an earthquake.
22.) Tsunami, Volcanic eruption.
24.) (a) False (b) True (c) False (d) False (e) True (f) True (g) False
25.) (a) repel; attract (b) positive (c) negative (d) electrons (e) friction (f) repel (g) earthing (h) electric (i) plate
SHORT ANSWER TYPE QUESTIONS :
26.) When we rub the plastic comb with our dry hair, the plastic comb gets electric charge due to friction. The electrically charged comb then exerts an electric force on the tiny pieces of paper and attracts them.
27.) By using silk cloth.
28.) By using a woolen cloth we will charge a inflated rubber balloon by the method of friction.
29.) With the friction of hair or friction of woolen cloth.
30.) The friction of two ball pen refill can charge two ball pen refill.
31.) Electroscope will show that the negative charge on the meter.
32.) Electroscope will show that the negative charge on the meter. The plastic comb gets electric charge due to friction.
33.) 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.
34.) When we touch a charged object, our body conducts its charges to the earth. That is why a charged body loses its charge, if we touch it with our hand.
35.) It will be turned into Earthquake.
37.) With the help of electroscope.
38.) It might be dangerous because lighting may strike the top end of the metal rod of umbrella.
39.) The person Should place his hand on his knees with his head between the hands. This position will make the make the person the shortest object around which is unlikely to be hit by lightning.
40.) Three measures are :
- We should avoid raising an umbrella over the head during lightning.
- The TV antennas and dish antennas fixed on tall buildings are especially prone to lightning areas.
- Lightning can strike metal pipes. Fixed in buildings. So, during a thunderstorms when lighting is taking place, we should avoid touching the metal pipes fixed in a house or buildings.
42.) a> Thick strip of metal.
c> Highest point of the building.
d> Buried deep in the ground near the building.
43.) The precautions are :
- We should take shelter under a sturdy table or a kitchen counter
- We should stay away from tall and heavy objects
- If we are in bed, we should just move on the bed to be close to a wall but not get up from the bed.
44.) The precautions are :
- We should stay at a clear spot away from buildings, trees and over-head power lines etc.
- If we are in a car, we should not come out of it. The car or bus should be driven slowly.
LONG ANSWER TYPE QUESTIONS :
46.) The electroscope is a device for device for detecting charge on an object.
47.) (a) The bright flash of light which we see in the clouds is called lightning.
Lightning is an electric discharge in the atmospheric between oppositely charged clouds.
(b) Objects on the ground have very little influence on its travelling path, until the stroke comes to a distance very close to the ground. That’s why lightning usually strike tall buildings.
(c) when lightning strikes the earth,it can be cause a lot of destruction by damaging property, tress and killing people.
48.) (a) If lightning strikes, it will hit the top of the lightning conductor. The electric energy of lightning passes through the metal strip and gets dischargesd safely into the ground through the buried metal plate.
The lightning conductor was invented by Benjamin Franklin.
(b) Lightning strikes are more frequent in the hilly areas because such areas clouds are comparatively closer to the ground.
49.) Earthquake is a destructive natural phenomenon which cannot be predicted is advance.
Two main situations are : a> Slide past one another.
b> Collide with one another.
(b) The place inside the earth crust where the earthquake is generated, is called focus
The point on earth’s surface directly above the focus is called epicenter.
50.) Three layers of earth are : Core, Mantle, Crust.
Seismograph is an instrument which measures and records the magnitude of an earthquake in terms of the shock waves it produces.