<< Chapter < Page Chapter >> Page >

Some animals can detect magnetic fields, whichhelps them orientate themselves and navigate. Animals which can do this include pigeons, bees, Monarch butterflies, sea turtles and certain fish.

The earth's magnetic field

In the picture below, you can see a representation of the earth's magnetic field which is very similar to the magnetic field of a giant bar magnet likethe one on the right of the picture. So the earth has two sets of north poles and south poles: geographic poles and magnetic poles .

The earth's magnetic field is thought to be caused by flowing liquid metals in the outer core which causes electric currents and a magnetic field. From the pictureyou can see that the direction of magnetic north and true north are not identical. The geographic north pole , which is the point through which the earth's rotation axis goes, is about 11,5 o away from the direction of the magnetic north pole (which is where a compass will point). However, the magnetic poles shift slightly all the time.

Another interesting thing to note is that if we think of the earth as a big bar magnet, and we know that magnetic field lines always point from north to south , then the compass tells us that what we call the magnetic north pole is actually the south pole of the bar magnet!

Interesting fact

The direction of the earth's magnetic field flips direction about once every 200 000 years! You can picture this as a bar magnet whose north and south poleperiodically switch sides. The reason for this is still not fully understood.

The importance of the magnetic field to life on earth

The earth's magnetic field is very important for humans and other animals on earth because it protects us from being bombarded (hit) by high energy charged particles which are emitted by the Sun. The stream of charged particles (mainly positively charged protons and negatively charged electrons) coming from the sun is called the solar wind. When these particles come close to the Earth, they become trapped by the Earth's magnetic field and cannot shower down to the surface where they can harm living organisms. Astronauts in space are at risk of being irradiated by the solar wind because they are outside the zones where the charged particles are trapped.

The region above Earth's atmosphere in which charged particles are affected by Earth's magnetic field is called the magnetosphere. Relatively often, in addition to the usual solar wind, the Sun may eject a large bubble of material (protons and electrons) with its own magnetic field from its outer atmosphere. Sometimes these bubbles travel towards the Earth where their magnetic fields can join with Earth's magnetic field. When this happens a huge amount of energy is released into the Earth's magnetosphere, causing a geomagnetic storm. These storms cause rapid changes in the Earth's magnetosphere which in turn may affect electric and magnetic systems on the Earth such as power grids, cellphone networks, and other electronic systems.

Aurorae (pronounced or-roar-ee)

Another effect caused by the Earth's magnetic field is the spectacular Northern and Southern Lights, which are also called the Aurora Borealis and the Aurora Australis respectively. When charged particles from the solar wind reach the Earth's magnetosphere, they spiral along the magnetic field lines towards the North and South poles. If they collide with particles in the Earth's atmosphere, they can cause red or green lights which stretch across a large part of the sky and which is called the aurora. Because this only happens close to the North and South poles, we cannot see the aurorae from South Africa. However, people living in the high Northern latitudes in Canada, Sweden, and Finland, for example, often see the Northern lights.

This simulation shows you the Earth's magnetic field and a compass.

run demo

Summary

  1. Magnets have two poles - North and South.
  2. Some substances can be easily magnetised.
  3. Like poles repel each other and unlike poles attract each other.
  4. The Earth also has a magnetic field.
  5. A compass can be used to find the magnetic north pole and help us find our direction.

This video provides a summary of the work covered in this chapter.

Khan academy video on magnets

End of chapter exercises

  1. Describe what is meant by the term magnetic field .
  2. Use words and pictures to explain why permanent magnets have a magnetic field around them. Refer to domains in your explanation.
  3. What is a magnet?
  4. What happens to the poles of a magnet if it is cut into pieces?
  5. What happens when like magnetic poles are brought close together?
  6. What happens when unlike magnetic poles are brought close together?
  7. Draw the shape of the magnetic field around a bar magnet.
  8. Explain how a compass indicates the direction of a magnetic field.
  9. Compare the magnetic field of the Earth to the magnetic field of a bar magnet using words and diagrams.
  10. Explain the difference between the geographical north pole and the magnetic north pole of the Earth.
  11. Give examples of phenomena that are affected by Earth's magnetic field.
  12. Draw a diagram showing the magnetic field around the Earth.

Questions & Answers

any tip for igcse economics exam?pls
Stacey Reply
well
The
What is a market
Divine Reply
what are the variables that affect demand
Divine
what are the variables that affect demand
Divine
what are the variables that affect demand
Divine
what are the variables that affect demand
Divine
what are the variables that affect demand
Divine
price of the related goods 2 price of the given commodity 3 income of the consumer 4 taste and preference 5 expectation in the future price
John
pls the taste and preference
Nas
explain briefly
Nas
a consumer taste and preference commodity changes for a time the man becomes
John
sorry sorry
John
is when the price of a commodity becomes high and can't afford example Samsung instead of iPhone
John
consumers who have high intense for goods will purchase the goods even if the price of that commodity increases because he or she preferred that commodity.people will be prefer iphone as its price increase
Yussif
as usual bad taste of preference is when a consumer regrets from one commodity to another in terms of the price
John
thanks alot
Nas
you're welcome
John
#Preference; #Income #Test
Dereje
#price Of Commodity #Income #Taste #Preference
Dereje
#Market is The Place Where Buyers And Sellers Are Exchanging Their Goods And service. #
Dereje
difference between macro and micro economics
Lawrence
Microeconomic Study about individual consumers market But Macroeconomis Study General economic Process Such As #Aggregate Demand #Aggregate Supples #GDp= #GNp
Dereje
nice so can u run down a brife discussion on GDP
Lawrence
good
Chinex
pls can someone differentiate between the perfectly elastic, perfectly inelastic and unitary
yhar Reply
and then again pls what are the types of elasticity, the methods of calculating it thank u
yhar
Perfectly inelastic is when the coefficient is equal to zero Unitary is when the coefficient is equal to one But am not sure if we have perfectly inelastic
John
I'm kind off confuse abt the PED, IED and co are they the types of elasticity we've
yhar
Yh the types are price elasticity cross and income elasticity of demand
John
do we've specific formulaes to calculate for each of them
yhar
yes. PED. changes in quantity demanded divided by changes in price
Vealmurugan
so pls what's the general name given to unitary, elastic n inelastic ? are the names given to the final result after doing the calculations?
yhar
P2-P1÷P1×100or Q2-Q1×Q1×100 PED
John
***tutor2u.net/economics/reference/price-elasticity-of-demand
Vealmurugan
They are elasticity coefficient
John
@John I don't get u well pls
yhar
whichone
John
P2-P1÷P1×100or Q2-Q1×Q1×100 PED @john pls tis is what m talking abt
yhar
Yh is the formula for PED
John
Pls are you having a for PED
John
thank u very
yhar
dy
Jobang
what is economics
Tayyeb
economics is a science which studies human behaviour as a relationship between ends and scarce means which have alternative use
John
is a science which study human behavior as a relationship between ends and scarce means which have alternative uses
Divine
yes this is because economic provide a body of knowledge on human economic principles under theories and these theories can be verified with real world data using science method in other words it was scientific method in arriving at solution identification of problem or basic data collection among
John
unitary ElasticWhen Elasticty =1 Perfectily Elastic When 0<1 inelastic when 0>
Dereje
Pls is anyone having the NovDec questions?
John Reply
No
Emmanuel
what is micro economics
Rakesh Reply
What is PPF
Endam
Production Possibility Frontier
John
It refers to a curve or graph which shows the possible contributions of maximum alternative of commodity that can be produced in an economy
John
thanks
Endam
Thanks John talkx of defination pls
Endam
I don't get you
John
guys Any One With Novdec Questions 2019?
Diana Reply
what did Adam Smith introduce?
Sunday Reply
what is supply
Awunyo Reply
supply relationship shows that the higher the price, the higher the quantity supplied. 
SDADY
what are the dissadvantages of large scale production
Atanga Reply
depreciate of quality taste
Kosiso
Some of the Disadvantages are:- 1. Production not according to individual Tastes 2. Monopoly 3. Not Flexible 4. Over-Production 5. Heavy loss and Dislocation 6. Decline of Cottage and Small Scale Industries 7. Adverse Effect on Labourers 8. Unequal Distribution of Wealth
Asrar
And what can be the advantages too
Enow
1.adequate satisfaction 2.reduce importation
Yussif
Reduce importation how pls
Enow
the country will have enough products.this will reduce the level of government expenditure on imported goods especially
Yussif
Some of Advantage 1. Division of Labour 2. More Production 3. Use of machines 4. Low Cost of Production 5. Standard Goods 6. Advertisements and Salesmanship
Asrar
Some of its disadvantages are : (i) Less Supervision (ii) Individual tastes ignored (iii) Absence of Personal Element (iv) Possibility of depression (v) Dependence on Foreign Markets (vi) International complications and war (vii) Cut-throat Competition (viii) Less Adaptability
Kalu
what are the types of trade cycle
Kenny Reply
depression
DG
explain the following 1.supply 2.mobility of labour 3.why the demand slope downward from left to right
Theresa Reply
Mobility of labor is a the movement of labor (people) geographically or occupationally
Olotu
What is Supply
Kamodu Reply
Supply is quantity of a comodity which is presented in the market for sell on fixed price
Mahwish
Supply is quality of a goods the seller are willing to deliver at the particular price
Chinex
what is economy
Jacob Reply
Economy is defined as the efficient use of resources
Thomas
explain merits and demerit of economic
Portia
What is Unemployment?
Prince Reply
unemployment is a situation where an individual is easily and ready to render services but resources are not available.
Phelix
Unemployment refers to individual who are employable and seeking a job but are unable to find a job or doesn't have a job. To find the unemployment rate in a given economy, you must divide the unemployed people by the total number of employed people in the work force. Indicator of economy's status.
elkanah
unemployment is The level of joblessness in an economy, often measured as a percentage of the workforce. Unemployment was reported at 5.2% in May, up from 4.9% in April
ANNOR
Pls wat are the factors that influence unemployment
Olotu
just trying ⚠ factors that affect unemployment - the rate of imported inflation - interest rates - levels of investment
Wallace
unemployment is a situation where country labour Force who are active capable and are really searching for or willing to work at assistant wage rates but cannot find job
John
working age ppl who have no job for a period of time. there are different types of unemployment like structural, fictional, seasonal n etc. there is a formula to calculate it. n have factors causes this.
Vealmurugan
factors that influence on employment 1 high population growth growth as against low Industries growth rates 2 lack of skills or mass irritracy 3 government policies such as minimum wage trade liberalization and high taxation 4 initial capital requirements
John
I'm an economics student, what I do now will make my life a success,
mostafiz
Thank you
Tantoh
😂😂😂😂😂😂😂☺☺☺🙂🙂🙂🙂🙂🙂🙂🙂🙂🙂🙂👩‍🎓👩‍🎓👩‍🎓👩‍🎓👩‍🎓👩‍🎓
Leta
what is difference between economic growth and economic development?( I want unique &brief answer)?
Leta
unemployment is when legitimate labour Force are not engaged in the economy.
Lawrence
economic growth is the already settled growth of the economy and National income can be used in verification of that while economic development is the process of improvement in an economy
Lawrence
what is rational behavior
Aaron Reply
James what is nationalisation
Awunyo
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Physics - grade 10 [caps 2011]. OpenStax CNX. Jun 14, 2011 Download for free at http://cnx.org/content/col11298/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Physics - grade 10 [caps 2011]' conversation and receive update notifications?

Ask