You Need to Know This to Measure the Distance Between a Seismograph and an Earthquake Epicenter.
Living Scientific discipline 2019 Solutions for Grade 8 Science Affiliate 14 Some Natural Phenomena are provided here with simple step-by-step explanations. These solutions for Some Natural Phenomena are extremely popular among Class 8 students for Science Some Natural Phenomena Solutions come handy for apace completing your homework and preparing for exams. All questions and answers from the Living Science 2019 Book of Form 8 Scientific discipline Affiliate 14 are provided here for you lot for gratis. You will likewise dearest the ad-free experience on Meritnation'due south Living Scientific discipline 2019 Solutions. All Living Science 2019 Solutions for form Grade 8 Science are prepared by experts and are 100% accurate.
Page No 185:
Question 1:
There are two kinds of charges. How do nosotros know this?
Respond:
When charges are brought shut to each other, sometimes they attract each other and sometimes they repel each other. Hence, we can conclude that there are two types of accuse nowadays in nature.
Page No 185:
Question 2:
What issue do the ii kinds of charges accept on each other?
Answer:
The 2 kinds of charges are basically positive charges and negative charges. They always concenter each other.
Folio No 185:
Question three:
Where practice the two kinds of charges come from?
Answer:
At that place are two kinds of charges nowadays in nature, positive charges and negative charges. The negative charges come from an excess of negatively charged particles and the positive charges come up from an excess of positively charged particles.
Page No 185:
Question iv:
Two objects rubbed against each other learn charge.
a. What is the relationship between the charges acquired past the two objects?
b. What action does rubbing crusade, considering of which the objects learn accuse?
Respond:
(a) The charges caused past the two objects are opposite in nature but are the same in magnitude.
(b) While rubbing, some of the negatively charged particles move from one object to another object. Due to that 1 object is left with an excess of negatively charged particles and another with an backlog of positively charged particles. That'south why both the objects acquire charge.
Page No 190:
Question ane:
An electroscope is used to detect and measure charges. What happens in an electroscope when its disc is touched with a charged object?
Respond:
When the disc is touched with a charged object, the charge distributes on both the strips of the electroscope. As both strips get like charges, so they repel and it creates a departure betwixt the two strips.
Page No 190:
Question 2:
To notice the nature of charge on an object, will y'all use a charged electroscope or an uncharged one?
Respond:
I will use a charged electroscope so that I can detect the modify in the divergence of the strips of the electroscope. If the nature of the unknown charge would exist similar to the known charge of the electroscope, the difference of the strips would increase and if the nature of the accuse would be opposite to the known charge on the strips of electroscope and so the divergence would decrease. That's how we can find the nature of an unknown charge.
Page No 190:
Question iii:
Should the rod of the electroscope connecting the disc with the strips be made of a usher or an insulator? Why?
Answer:
The rod of the electroscope connecting the disc with the strips should exist fabricated of a conductor so that the charge given to the disc can distribute itself on both the strips of the electroscope. If it would be an insulator then the accuse given to the disc would not reach to the strips and strips will never diverge.
Folio No 190:
Question 4:
Air is an insulator, just can conduct electricity under sure conditions. What are these conditions? What is conduction of electricity through air chosen?
Answer:
Air allows electricity to pass through it if the quantity of the charge is large and the altitude is pocket-sized. In such a situation a very heavy charge passes through the air in a very short span of time. The conduction of electricity through the air is known equally Electrical discharge.
Page No 190:
Question 5:
If lightning strikes a building, information technology flows harmlessly through the lightning conductor. What belongings should the material of which the lightning conductor is made have, to make this possible?
Reply:
The lightning conductor is made of a metallic rod ending in spikes at the top which is connected to a copper plate buried deep within the ground. If lightning strikes a building the metallic rod attracts the excess of accuse and pass it to the ground.
Page No 193:
Question 1:
By how many times is an earthquake of magnitude 5 on the Richter scale more powerful than one of magnitude 4?
Respond:
On the Richter scale, an earthquake of magnitude 5 is 10 times more powerful than one of magnitude iv.
Page No 193:
Question 2:
Which of these lies on the earth's surface- seismic focus or epicentre?
Reply:
Epicenter lies on the surface of the earth while seismic focus lies within the crust of the earth.
Page No 193:
Question three:
Earthquakes are almost likely to occur in fault zones. Where are these fault zones normally situated?
Answer:
Earthquakes are virtually likely to occur in mistake zones. These fault zones lie at the boundaries of the tectonic plates.
Page No 193:
Question 4:
During an convulsion, you lot should take shelter in high-rise buildings. Exercise you agree? Give reasons.
Reply:
High-rising buildings are near likely to autumn during an earthquake. So, we should not have shelter in a loftier-rise building. Instead, we should leave the building and come up out in the open up ground.
Folio No 195:
Question one:
Like charges
(a) always repel each other.
(b) ever attract each other.
(c) tin repel or concenter each other depending on atmospheric condition.
(d) can repel or attract each other depending on the quantity of charge.
Answer:
(a) always repel each other
Two like charges always repel each other.
Page No 195:
Question 2:
A torso can exist charged past
(a) rubbing it confronting another body.
(b) touching it to a charged torso.
(c) bringing a charged trunk about it.
(d) all of the above methods.
Respond:
(d) all of the to a higher place methods
An uncharged trunk tin can be charged when it is rubbed confronting some other torso, touched with a charged body or brought about a charged body.
Page No 195:
Question 3:
When two bodies are rubbed against each other,
(a) they larn equal and similar charges.
(b) they acquire equal and contrary charges.
(c) they acquire unequal and similar charges.
(d) they acquire unequal and opposite charges.
Answer:
(b) they acquire equal and opposite charges
When two bodies are rubbed against each other, they larn equal and opposite charges because on rubbing, charges move from ane body to another.
Folio No 195:
Question 4:
The gold-leaf electroscope tin can be used to
(a) detect accuse only.
(b) detect and measure charge simply.
(c) detect, measure and observe the nature of accuse.
(d) none of the to a higher place
Answer:
(c) detect, measure out and find the nature of accuse
Page No 195:
Question 5:
Electric accuse tin can period through
(a) insulators.
(b) conductors.
(c) both insulators and conductors.
(d) neither insulators nor conductors.
Reply:
(b) conductors
Electric charge can flow through a conductor but not through an insulator.
Page No 195:
Question half-dozen:
A lightning conductor is a
(a) piece of wire with spikes through which current can period.
(b) substance that can exist charged by clouds.
(c) metal rod with spikes, ending in a copper plate buried in the basis, fixed to a edifice to protect it from lightning.
(d) copper plate buried in the ground below a edifice to protect it from lightning.
Answer:
(c) metal rod, with spikes ending in a copper plate buried in the ground, fixed to a building to protect information technology from lightning
Page No 195:
Question 7:
To test if a body is charged or not you volition utilise
(a) another uncharged body.
(b) a positively charged body.
(c) a negatively charged body.
(d) a positively and a negatively charged body.
Answer:
(d) positively and negatively charged bodies
To examination whether a body is charged or not, we volition bring information technology close to positively and negatively charged bodies because an uncharged body is attracted past both positively and negatively charged bodies.
Folio No 195:
Question 8:
Yous are given an uncharged electroscope and a charged body. No other appliance is allowed. You can use the electroscope to
(a) only notice the accuse.
(b) detect and measure the accuse.
(c) observe, measure and observe the nature of the charge.
(d) neither of these since the electroscope is uncharged.
Answer:
(b) detect and measure out the charge
We can simply detect and measure charge using an uncharged electroscope and a charged body. To test the nature of the charge, nosotros need some other body with a known charge.
Page No 195:
Question 1:
When charges of static electricity flow through conductors we become electric current electricity. True or simulated?
Answer:
True.
The menses of charge in a usher is called an electric current.
Page No 196:
Question 2:
2 combs made of the same material are rubbed against your pilus and brought near each other. Will they concenter or repel each other?
Answer:
When two combs made of the same textile are rubbed against hair, they acquire the same nature of charge. Then, when they are brought nigh, they repel each other.
Page No 196:
Question 3:
A negatively-charged object will __________ a positively-charged object.
Answer:
A negatively charged object will attract a positively charged object.
Folio No 196:
Question 4:
What kind of charge is produced in a silk cloth when it is rubbed against a glass rod?
Answer:
When a silk cloth is rubbed against a glass rod, the glass rod becomes positively charged and the silk fabric becomes negatively charged.
Page No 196:
Question 5:
Under normal circumstances atoms contain equal number of positive and negative charges. True or fake?
Answer:
True.
Nether normal circumstances, in an atom, the number of particles with negative charge (called electrons) is equal to the number of particles with positive charge (called protons).
Page No 196:
Question vi:
Which charges in an atom are more than free to movement nigh−positive or negative?
Reply:
In an atom, the negatively charged particles (chosen electrons) are more than gratis to move than the positively charged particles (called protons).
Folio No 196:
Question 7:
Charging a torso by bringing a charged body near information technology, but not touching information technology is called charging by __________
Reply:
Charging a body by bringing a charged trunk near it but not touching information technology is called charging by consecration.
Page No 196:
Question 8:
Charging a body by touching it with a charged torso is called charging past __________
Answer:
Charging a body by touching it with a charged body is chosen charging by conduction.
Page No 196:
Question 9:
Name the instrument used for detecting and measuring accuse.
Answer:
Electroscope is used for detecting and measuring charge.
Page No 196:
Question 10:
To observe the nature of charge using a gilt-foliage electroscope, should the electroscope be initially charged or uncharged?
Respond:
To check whether a trunk has a positive or negative charge, it is necessary to accuse the electroscope with a known charge.
Page No 196:
Question 11:
What is the period of charge chosen? Can accuse menstruum through an ebonite rod?
Reply:
The flow of charge in a conductor is called an electric current. Charges cannot flow through an ebonite rod because it is an insulator.
Page No 196:
Question 12:
The menses of heavy accuse through air, accompanied past heat and light is called __________
Answer:
The menstruum of heavy accuse through air accompanied past heat and calorie-free is called lightning.
Folio No 196:
Question xiii:
Lightning is due to menses of charge between clouds. True or faux?
Respond:
False. Lightning is due to the discharge of two static unlikely charged clouds when they come up close to each other.
Page No 196:
Question 14:
An electroscope is charged by induction using a negatively-charged trunk. What charge will the electroscope acquire − positive or negative?
Respond:
When an electroscope is charged by induction using a negatively charged body, information technology acquires the reverse kind of accuse, i.east., positive.
Page No 196:
Question 15:
When charged by conduction a torso acquires the __________ (aforementioned/opposite) accuse as the charging body.
Reply:
When charged past conduction, a body acquires the aforementioned charge as the charging body.
Page No 196:
Question 16:
The intensity of an earthquake is measured on the __________ calibration.
Answer:
The intensity of an earthquake is measured on the Richter scale.
Folio No 196:
Question 17:
A __________ records the waves generated by an earthquake, known as __________ waves.
Answer:
A seismograph or seismometerrecords the waves generated by an earthquake. These waves are known as seismic waves.
Page No 196:
Question eighteen:
An convulsion is most likely to occur in the centre of the tectonic plates. True or false?
Answer:
Simulated. The boundaries of tectonic plates are the zones where earthquakes are nigh probable to occur.
Page No 196:
Question 19:
Volcanic activity tin likewise cause earthquakes. True or false?
Answer:
True.
During volcanic eruptions, very explosive trigger-happy gases motility upwards; this may pb to earthquakes.
Folio No 196:
Question 1:
Why does a comb rubbed on hair attract pieces of paper?
Answer:
When a comb is rubbed on hair, information technology gets charged. When this charged comb is brought near uncharged pieces of paper, they get attracted towards the comb.
Folio No 196:
Question 2:
Under what weather practise charges attract or repel each other?
Answer:
Two like charges (positive or negative) repel each other and two unlike charges (one positive and one negative) always concenter each other.
Page No 196:
Question 3:
Why practise nosotros say that only repulsion is a sure examination of charge on a body?
Answer:
A charged body attracts a body with an contrary charge. It also attracts an uncharged body. That is why repulsion alone is a sure exam to check whether a body is charged or not.
Page No 196:
Question 4:
What do you hateful by 'charging by conduction'? What kind of charge does the trunk larn?
Answer:
Conduction is the process of charging a body by touching it to a charged body. In this process, the body that is being charged acquires the same kind of charge as the charging body.
Folio No 196:
Question 5:
What is 'charging by induction'? What kind of accuse does the trunk acquire?
Answer:
The process of charging a body by bringing a charged torso near it without touching it is called charging past consecration. In this procedure, the body being charged acquires the reverse kind of charge to that of the body charging information technology.
Folio No 196:
Question 6:
What is the difference between conductors and non-conductors? Give two examples of each.
Answer:
| Conductors | Non-Conductors |
| Charges tin flow through a usher. | Charges cannot flow through an insulator. |
| They bear electricity. | They do not comport electricity. |
| Examples: Copper and argent | Examples: Plastic and ebonite |
Folio No 196:
Question vii:
What is an electroscope?
Answer:
An electroscope is a device that is used to find, measure and observe the nature of accuse.
Page No 196:
Question eight:
What is 'earthing'?
Answer:
The process of transferring charges from a charged object to the earth is called earthing.
Folio No 196:
Question one:
Explain why, when two bodies, charged past rubbing them together, learn equal and reverse charge.
Answer:
In an atom, the positively charged particles are firmly bounded, whereas the negatively charged particles are loosely divisional. Then, when two bodies are rubbed together, some negatively charged particles move from one trunk to some other. Thus, the trunk losing negative charges becomes positively charged and the body gaining negative charges becomes negatively charged.
Page No 197:
Question 2:
What is the divergence between static and current electricity?
Reply:
| Static Electricity | Current Electricity |
| Static electricity is the written report of charges at residuum. | Electric current electricity is the study of charges in motility. |
| When a trunk is charged past rubbing, it acquires static electricity. | The flow of electric current in a conductor is called an electric current. |
Page No 197:
Question 3:
What is an electric discharge? Under what atmospheric condition does it occur?
Reply:
The loss of static electricity every bit charges motility from an object is called an electric discharge. When two objects with opposite charges come up shut to each other, there is a sudden period of electricity between them. For example, when two clouds with unlike charges come close to each other, a very heavy current passes through the air; this results in lightning.
Page No 197:
Question 4:
In what situation tin can lightning be dangerous? How tin can the danger to tall buildings exist reduced?
Answer:
Clouds can charge tall buildings by induction. The buildings, thus, larn the reverse charge. If the congenital-upwardly accuse is very heavy, a heavy flow of electric charge can occur between the clouds and the buildings. This can upshot in the buildings communicable fire. To protect tall buildings from damage past lightning, a lightning conductor is fixed on them. If lightning strikes a building, it flows harmlessly to the globe through the lightning conductor, causing no damage to the building.
Folio No 197:
Question v:
How does a lightning conductor work?
Respond:
To protect tall buildings from damage by lightning, lightning conductors are fixed on them. A lightning usher consists of a metal rod ending in spikes at the top. The lower terminate of the rod is attached to a copper plate buried deep in the globe. If lightning strikes a building, it flows harmlessly to the earth through the metal rod, causing no harm to the edifice.
Page No 197:
Question 6:
Listing 4 precautions you will take to save yourself from a lightning strike during a thunderstorm.
Answer:
We can accept the post-obit precautions to save ourselves from lightning strikes during a thunderstorm:
(one) Nosotros tin take shelter in a building with lightning conductor.
(two) A car or bus with airtight windows is also a safety place to take shelter.
(3) Nosotros should avoid taking shelter nether a alpine tree, as lightning may strike information technology.
(iv) An open elevated place is not a safe place to exist in. If in an open place, we should stay away from trees and poles.
Page No 197:
Question 7:
What is the Richter scale? Why do we say that information technology is non a linear scale?
Reply:
The magnitude or intensity of an earthquake is measured on the Richter scale. The number indicating the intensity of an earthquake on the Richter scale ranges from 0 to 9. The Richter scale is not a linear scale because the amplitude of vibrations of an earthquake varies nonlinearly with the number on the scale.
Page No 197:
Question 8:
List three effects of an convulsion.
Answer:
An earthquake may cause the following effects:
(1) It can result in the deformation of the surface of the ground.
(2) It tin damage human being-made structures such as buildings, roads, runway and bridges.
(3) It tin cause landslides and human being causalities in hilly areas.
Page No 197:
Question ane:
Draw a labelled diagram of a gold-leaf electroscope. Draw how you lot will utilise it to notice a charge, measure a charge, and observe the nature of the charge.
Reply:
Gold-leaf Electroscope
Process to Detect and Measure Charge
If a charged body (for instance, ebonite rod) is touched to the metal disc of the golden-leaf electroscope, the metal strips of the electroscope gets charged by conduction. They repel each other and open up upwardly. In this mode, we can discover whether an object is charged or non.
Process to Know the Nature of Charge
To cheque whether a body has a positive or negative accuse, we demand a charged electroscope with a known accuse. Nosotros need to touch the charged body to the metal disc of the electroscope. If the deviation of the leaves increases, the body has a charge similar to that of the charged electroscope; and if the difference of the leaves decreases, the trunk has a charge reverse to that of the electroscope.
Page No 197:
Question 2:
Explicate how lightning occurs between 2 clouds during a storm.
Answer:
During a storm, air currents with small water droplets move upwardly, while those with big water droplets move downwardly. These vigorous movements cause the separation of charges due to friction. The positively charged low-cal droplets get collected near the upper edges of the clouds, while the negatively charged big h2o droplets get accumulated near the lower edges. There is also accumulation of positive charges nigh the ground because of induction. When the magnitude of the accumulated charges becomes very big, the air between the two clouds (with unlike charges), which is an insulator, no longer resists these clouds. Equally a result, the negative and positive charges run across, producing streaks of vivid light and sound due to electrical discharge. This procedure is called lightning.
Folio No 197:
Question three:
Explain the process of lightning striking a edifice or tree.
Reply:
Clouds tin can accuse tall buildings or copse. The negative charge on the lower border of the clouds leads to aggregating of positive charge on the upper portion of the buildings or trees due to induction. If the magnitude of the accumulated charges is very big, the air that acts equally an insulator betwixt the clouds and the buildings could no longer resists the charges. Equally a result, a very heavy charge passes through the air in short fourth dimension considering of the electric belch and huge amount of free energy releases in the form of heat, lite and sound. This procedure is chosen lightning. When lightning strikes a building or tree, it catches fire because of the huge corporeality of free energy released.
Page No 197:
Question four:
In what ways is lightning useful?
Answer:
Lightning is useful to us in the following ways:
(1) The oestrus and light released during lightning enable nitrogen in the air to combine with oxygen to form oxides of nitrogen. These become dissolved in water to form dilute nitric acid that comes down with rain. The acid reacts with salts in the soil to form nitrogenous compounds that are essential for the growth of plants.
(ii) Lightning also enables ozone to exist formed from the oxygen in the air. The ozone nowadays in the air stops the harmful ultraviolet rays of the sun from reaching us.
Folio No 197:
Question 5:
Explain how an earthquake occurs.
Answer:
Earthquakes are caused by disturbances deep downward the uppermost layer of the earth known as the crust. The tectonic plates of the earth float over the hot magma below and are in relative motion to each other. When these plates collide and when the rocks at the joints are sufficiently glace, the plates slide over each other. However, sometimes, the rocks at the joints go interlocked and struck, thus resisting pressure from within. For years, the forces pushing the plates build up until the strain rips the plates autonomously. Every bit a outcome, the rocks crevice and shift, sending shock waves in all directions. These waves reach the surface and are felt as tremors.
Page No 197:
Question half dozen:
List three things you volition do during an earthquake.
Respond:
We should practice the post-obit things during an earthquake:
- We should leave the edifice where we are and move to some open area. In outdoors, nosotros should be away from high buildings, copse, electric poles, etc.
- If we are trapped in a edifice, we should take shelter under a tabular array, protecting our head with hands, and should not move until the shaking stops. It is improve to avoid lift during an earthquake.
- If we are in a motorcar or motorcoach, nosotros should not come out until the tremors stop.
Page No 197:
Question i:
Why are taller buildings in greater danger of being struck past lightning?
Answer:
Lightning is a fairly random occurrence. It may strike a alpine building or a small-scale house. Simply it causes greater danger to a alpine building considering a lot of material is used in its structure. If lightning strikes a tall edifice, the huge current involved tin estrus the building textile to a high temperature, causing a potential for burn down.
Page No 197:
Question 2:
When a positively-charged body is brought nigh an uncharged metal rod, the office of the rod near the charged body acquires a negative charge, and the far side a positive charge. Can you lot say why this happens? Remember that in a body, negative charges are mobile whereas positive charges are stock-still.
Answer:
When a positively charged body is brought near an uncharged metallic rod, the office of the rod near the charged body acquires a negative charge because of the procedure of consecration. The positively charged torso attracts the negative charges, i.eastward., electrons towards information technology. The negative charges become accumulated near the end of the metallic rod. The far cease of the rod becomes positively charged because of the deficiency of negative charges .
Page No 197:
Question iii:
If you hold a plastic rummage in your hand and rub it in your hair, it will get charged. However, if you do the same with a metal comb information technology volition not go charged. Why? But if the metal comb has a plastic handle and you hold it from the handle, information technology will besides get charged. Why?
Answer:
Plastic is an insulator, whereas metals are proficient conductors of electricity. When a plastic comb is rubbed on our hair, it acquires static charges, which exercise non move. If we exercise the same with a metal rummage, it volition not hold static electricity; the charges move from the comb to our body. But if the metallic comb has a plastic handle, it volition hold the charges, equally the charges cannot movement from the comb to our body.
Page No 197:
Question 4:
Why do you think charging by rubbing happens best in dry weather?
Answer:
Charging past rubbing happens all-time in dry weather. Air is an insulator, but the presence of wet in air makes it conductive, which, in turn, makes static charges to flow through the air to brand the object electrically neutral. Considering the moisture level is quite low in dry weather, charging happens best in it.
Page No 197:
Question v:
The rod of a lightning conductor accidentally broke into two from the heart. What danger will this pose if lightning strikes the building? Why?
Answer:
If the rod of a lightning usher installed in a building accidently breaks into two from the middle and lightning strikes that edifice, it can cause huge damage to life and property. The heavy charges would easily find another conductive path through the edifice structure such as building wiring or plumbing and crusade fire or other disaster.
Page No 197:
Question 1:
An aircraft flies just below a negatively charged thundercloud.
Answer these questions.
i. Will any electrostatic charges be included on the aircraft?
2. If and so, describe the signs and positions of the induced charges on the aircraft.
3. Explain the distribution of the charges that you have shown on the basis of the movement of electrons.
4. Depict a diagram to show the charges after the aircraft has flown away from the deject.
5. Explain the distribution of charges you lot accept shown in Ans. 4 on the footing of the motion of electrons.
Answer:
(1) Yep, aircraft is fabricated up of conducting material, and so the electrostatic accuse volition become induced on the surface of shipping.
(2) Induced charges on the shipping:
(3) When an aircraft passes below the negatively charged cloud, due to the force of repulsion of negative accuse from the cloud, the electrons on the surface of shipping shift away from the surface and leave the surface positively charged. Every bit y'all can run into in the above figure. Due to the movement of electrons, the surface of the aircraft becomes positively charged while the bottom of the aircraft becomes negatively charged.
(iv) Afterwards the aircraft has flown away from the cloud:
(5) Equally presently as the aircraft passes the deject, the charges redistribute themselves to their original places. The electrons which moved to the bottom of the aircraft due to the presence of highly negatively charged cloud, render to their original places and neutralize the positive charge.
Page No 198:
Question 1:
When an convulsion suddenly struck Rani'south village, she shouted to tell the people that they should come out of their houses and go into the fields, since at that place were no trees, electric poles or buildings nearby.
Later she went about organizing assistance for the injured and people who had been rendered homeless.
What values did Rani show?
Answer:
Rani showed the following values:
(i) Rani is an intelligent girl. She knows exactly what to do when an earthquake hits.
(ii) She is also very caring, supporting and a responsible citizen of the society considering she does not save only herself but also tells other people to come out in the open and save themselves. Subsequently she participates in helping the injured people too.
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