Author Topic: ALL PHYSICS DOUBTS - POST HERE !!  (Read 225508 times)

Offline Ivo

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1785 on: May 26, 2010, 10:52:55 am »
What abt this one ::) I really don't get it?   ???

Four metal rods are placed, in turn, inside a coil of copper wire.
Which rod would be the most suitable to use for the core of a coil in a circuit breaker?

number of paper clips picked up when there is a current in the coil:     number of paper clips still attracted when the current is switched off:
A                                 1                                                                                            0
B                                 20                                                                                           2
C                                 35                                                                                           0
D                                 35                                                                                           30





C, right.  Cos you want a electromagnet which magnetisises and demagnetises easily.  Electromagnets lose magentism when current is siwtiched off, that's why it's zero when off.
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6394

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1786 on: May 26, 2010, 10:53:37 am »
@ kimo jesus n dana wen r u ppl gettin ovr wid phy ppr 1
because m done  ??!11??!!

Offline dodi23

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1787 on: May 26, 2010, 10:54:38 am »
soo how wz it??
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Offline Ghost Of Highbury

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1788 on: May 26, 2010, 10:54:59 am »
aadi  for u

a women tune her radio to a station broadcasting on 200m

what does 200m tell her about the radio wave?

freq

wave leng

sped

ampl

if m is meter, shud be wavelength. although, the wavelength of medium wave radio is 100 m...anyway...
divine intervention!

Offline Dana

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1789 on: May 26, 2010, 10:56:09 am »
C, right.  Cos you want a electromagnet which magnetisises and demagnetises easily.  Electromagnets lose magentism when current is siwtiched off, that's why it's zero when off.
That's what I was thinking.. I'll check and tell you. Thanks alot!

Offline Dana

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1790 on: May 26, 2010, 10:56:43 am »
@ kimo jesus n dana wen r u ppl gettin ovr wid phy ppr 1
because m done  ??!11??!!
My exam's in about 2 hours
how was it???

Offline Weaam

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1791 on: May 26, 2010, 10:56:58 am »
Can anyone tell me how to magnetise steel?
And how to demagnetise it?
Thank You! ;D
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Offline WARRIOR

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1792 on: May 26, 2010, 10:57:14 am »
What abt this one ::) I really don't get it?   ???

Four metal rods are placed, in turn, inside a coil of copper wire.
Which rod would be the most suitable to use for the core of a coil in a circuit breaker?

number of paper clips picked up when there is a current in the coil:     number of paper clips still attracted when the current is switched off:
A                                 1                                                                                            0
B                                 20                                                                                           2
C                                 35                                                                                           0
D                                 35                                                                                           30




its C

why? caz elctro magnets should be magnetic whn the current is switched off !

and which attraacts more  A or C ..whn current is on? C

im doin the exam in 2 hours an haa half
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Offline Ivo

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1793 on: May 26, 2010, 10:57:31 am »
Can anyone tell me how to magnetise steel?
And how to demagnetise it?
Thank You! ;D

https://studentforums.biz/index.php/topic,7946.msg210346.html#msg210346
Always willing to help!  8)
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Offline the_grim_reaper

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1794 on: May 26, 2010, 10:57:45 am »
@ kimo jesus n dana wen r u ppl gettin ovr wid phy ppr 1
because m done  ??!11??!!

Don't worry Lad. It's still 12:55 PM in KSA and my paper is at 3 PM. So there's still A LOT of time left for everyone to get rid of paper 1 :D :D.

(Don't worry I don't want to know if it was hard or easy or whatever. If I fail, I'll fail on my own. It I pass, I'll pass on my own. Way of the Samurai :D :D :D)....

Offline Ivo

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1795 on: May 26, 2010, 10:58:17 am »
Can anyone please clear doubt about magnetism.  So ferrous materials can be magnetised (e.g. iron and steel).  All ferrous materials can be magnetically induced (so both sides of a magnetic object attracts).  

However, a magent has poles.  To make magnet, you place in d.c. current.

I'm not sure, but am i right in saying that in magnetic induction, the thing being induced is not a magnet, because it does not have magnetic field lines?

By the way, iron is magnetically soft, so loses magnetism easily right?


Please can someone answer my qu. thanks a lot!
Always willing to help!  8)
"In helping others, we shall help ourselves, for whatever good we give out completes the circle and comes back to us."

Offline Dana

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1796 on: May 26, 2010, 10:58:38 am »
its C

why? caz elctro magnets should be magnetic whn the current is switched off !

and which attraacts more  A or C ..whn current is on? C

im doin the exam in 2 hours an haa half
Thanks :)

Offline Dana

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1797 on: May 26, 2010, 10:59:51 am »
Don't worry Lad. It's still 12:55 PM in KSA and my paper is at 3 PM. So there's still A LOT of time left for everyone to get rid of paper 1 :D :D.

(Don't worry I don't want to know if it was hard or easy or whatever. If I fail, I'll fail on my own. It I pass, I'll pass on my own. Way of the Samurai :D :D :D)....
Noooo I wanna know if it was easy or difficult! So i can brace myself uno? :P
I'm doing it in Saudi too! Which city are you in?

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1798 on: May 26, 2010, 11:00:27 am »
How ???

See below.

Offline Vin

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1799 on: May 26, 2010, 11:01:57 am »
How ???

See below.

you can place it in a known Temperature .. to calibrate