June 2011 G485-Fields, Particles and Frontiers of Physics

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Reply 820

susan23

sun gives out energy in the form of electromagnetic waves? yh?

Reply 821

ViralRiver

Can someone explain the acoustic impedance equation?

Reply 822

Haraze

Original post by ViralRiver

Can someone explain the acoustic impedance equation?

It's Z=rho x c, where Z is the acoustical impedance, rho is the density of the material and c is speed of sound.

(edited 12 years ago)

Good morning folks!

I finally understand olbers' paradox :biggrin:

Reply 826

TobeTheHero

Original post by gradu

Fixed.

cheer up :biggrin:

lets smash this!

Reply 827

Ralphus J

How the **** were you up at 4 AM!

Who wants to tell me the main things of electromagnetic induction?

Reply 828

TobeTheHero

Original post by Ralphus J

How the **** were you up at 4 AM!

Who wants to tell me the main things of electromagnetic induction?

hahah I'm determined to smash this paper! I'll do whatever it takes!

here are the main points of electromagnetic induction

1) E Induction is basically the Generation of e.m.f from moving a coil through a magnetic field or visa versa (moving the magnet) electrons experience a force hence charge accumulates at one end :smile:

2) Faraday's Law

the e.m.f induced=-the rate of change of flux linkage

flux linkage=BAN B=magnetic flux density A=Area of the coil N=number of turns

the minus sign indicates that this e.m.f opposes whatever it is causing it :smile:

Lenz's law

3) Lenz's law states that the direction of any induced current is in a direction that opposes the flux change that causes it :smile:

4) Transformers work by electromagnetic induction. They use Electromagnetic induction to change the size of the voltage for an alternating current.

5) Generators work by converting KE into electrical energy. It does this by inducing a current by rotating a coil in a magnetic field

(edited 12 years ago)

I'm tired

6 hours sleep, then did some semi-sleep in my head revision :flutter:

Reply 831

TobeTheHero

Original post by Oh my Ms. Coffey

6 hours sleep, then did some semi-sleep in my head revision :flutter:

I just couldn't sleep last night :frown:

my mind was on C4 :mad:

so I decided to just lay down close eyes for full 3 hours! here I am this morning having not slept at all :eek:

I just went through module 5 and I'm done :biggrin:

Now it's all just reviewing last night's work :wink:

Reply 832

TobeTheHero

Original post by Pheylan

I'm tired

At least you slept for some hours!

good luck guys!

For LHR and RHR you use conventional current or electron flow?

Reply 835

TobeTheHero

Original post by Ralphus J

For LHR and RHR you use conventional current or electron flow?

Conventional :smile:

Reply 836

Rosieretops

I had a dream about Physics and then I woke up and immediately defined magnetic flux. It was really weird. Anyway good luck everyone I hope it's an alright exam and that there is actually enough time to complete it!

Reply 837

Pheylan

Original post by Rosieretops

I had a dream about Physics and then I woke up and immediately defined magnetic flux. It was really weird.

Once I woke up and knew how to win a game of noughts and crosses :confused:

Another time I woke up and spelt 'antidisestablishmentarianism' for the first time

(edited 12 years ago)

Reply 838

jamedz

How did everyone find it then? :smile:

Reply 839

Pheylan

Thought it wasn't too bad, but I ran out of time :s-smilie:

had a few minutes to go back and scribble some answers to some of the essay type questions. Did anyone else get 1/81 for the ratio in the capacitance question?