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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

An aircraft having a wingspan of 20.48 m flies due north at aspeed of 40 ms^(−1). If the vertical component of earths magneticfield at the place is 2 × 10^(−5) T, Calculate the emf induced between the ends of the wings

this problem is in my physics book?

my question is that how would an emf be induced between the ends of the wings.

upto my knowledge i can't imagine it technically.can somebody explain it?

*Last edited by yazz (2014-02-11 00:10:43)*

Knowledge is knowing that a tomato is a

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Perhaps because a moving conductor that is moving through a magnetic field would be cutting the magnetic lines of force. That would generate a small emf.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

oh thank you .i thought of it after posting it.

and another doubt. how does a digital clock work.

i know about the internal working .but how would you get the time into the display.or more specifically, how does the chip inside the watch work? are they programmable or a kind of preprogrammed ROM.

and another doubt -how people found the radius of the earth as 6371 km.

when i asked the question with my teacher a few years ago, she just starred at me and the period ended.

Knowledge is knowing that a tomato is a

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

In the old days of digital circuitry we would use a 555 timer to generate pulses and then a counter circuit to increment each time a pulse was sent to it. Then there would be some need for a multiplexer ( I think ) to light up the LED chips in a way that keeps time.

The ancient Greeks did that calculation. You should look it up, the inventor was a genius.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

if you know how they did please post it.

Knowledge is knowing that a tomato is a

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Hi;

Have you searched Google for Eratosthenes? he is the one who did the calculation. This is quite a coincidence because he also invented the sieve of Eratosthenes which the guy in the other thread is taking credit for!

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

yeah it was very interesting.

and whats the 555 timer.

you have said that it was in the olden days of circuitry!how would it look in the digital watches at the present age.

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Hi yazz;

Probably the whole thing has been put into a single chip or even a small microprocessor.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

hi,bobbym,

really thank you for spending some time and sharing your knowledge for my obviously simple question.

very kind of you.:)

se you tomorrow.BTW you are banned for answering my question.

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Hi jazz;

Do not get carried away. Everything I used to know about electronics I forgot. It is probably all wrong. You can ban me for that.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

noooo.its fine....its hard to find teacher (atleast for me) like you.

ok i don't get carried away...

when i asked the question with my teacher a

few years ago, she just starred at me and the

period ended.

al l of our school teachers are like that.and i just lost interest in asking doubts.i should have been lucky to find you for atleast you are better than my teachers!

*Last edited by yazz (2014-02-11 01:34:06)*

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

My teachers were pretty good but I did not want to listen to them. You want to listen to them but they are not good. Isn't the world a confusing place? Shouldn't I have had your teachers and you mine?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

:'( yeah.that is the philosophy of life....

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Maybe next time it will be different.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

what?i can't get you!

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Oh, I am sorry. You are not Hindu, I thought you were.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

no i aam HINDU.your first thought was correct!

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Then pardon me for asking then you know that this lifetime is just a single breath, a single life in a sequence of them. Hinduism is not the only philosophy that believes in reincarnation although it might have been the first human one to.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

Then pardon

no i don't really care about that!some say that there is rebirth.if there is so then we shall wish that our teachers should be swapped!

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Yes, but probably I will want to listen to them and they will not want to teach.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**yazz****Member**- Registered: 2014-01-14
- Posts: 425

pgood joke .ok bye.i really had a good time to spend with you. my mom is scholding now.see you later

fruit, but Wisdom is knowing not to put it in a fruit salad .

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,321

hi Yazz,

Didn't realise your question had developed into another about the radius of the Earth.

Eratosthenes noticed that, on mid summer's day, the Sun was directly overhead in Syene. He knew this because the Sun's light got right down to the bottom of a deep well there. But, on the same day, if he was in Alexandria, the Sun was about 7 degrees from the vertical. He reasoned that the Earth must be spherical for this to happen. By measuring the distance between the two towns he was able to estimate the circumference of the Earth. The value he got was amazingly accurate. (note: It isn't just the measurement that is remarkable, but also, that he was able to deduce the shape of the Earth itself!

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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