Questions

Discuss Physics and Physics Olympiad related problems here
bidrohi
Posts:33
Joined:Mon Dec 27, 2010 1:33 am
Questions

Unread post by bidrohi » Mon Dec 27, 2010 2:44 am

What'll happen if I start flowing positrons through electric appliances?

Electricity is flow of electrons & beta ray is also flow of electrons. So can electricity be produced using beta ray?

Magenta+Cyan+Yellow=? I've found in a book that its black but how?

If we can somehow defy gravity in vacuum, then will a generator rotate & produce electricity forever?

tanvirab
Posts:446
Joined:Tue Dec 07, 2010 2:08 am
Location:Pasadena, California, U.S.A.

Re: Questions

Unread post by tanvirab » Mon Dec 27, 2010 4:29 pm

Positrons will annihilate as soon as they come into contact with our electrical appliances.

Sure, if you know how to control Beta rays.

Gravity or vacuum has nothing to do with it. A generator can only produce as much energy as it is given as input.

bidrohi
Posts:33
Joined:Mon Dec 27, 2010 1:33 am

Re: Questions

Unread post by bidrohi » Mon Dec 27, 2010 9:32 pm

tanvirab wrote:Gravity or vacuum has nothing to do with it. A generator can only produce as much energy as it is given as input.
If I rotate the armature, it will stop because of gravity and friction. If it is vacuum then there will be no friction because of no air (except the friction in the parts), and by defying gravity the armature should rotate forever according to Newton's 1st law.

tanvirab
Posts:446
Joined:Tue Dec 07, 2010 2:08 am
Location:Pasadena, California, U.S.A.

Re: Questions

Unread post by tanvirab » Tue Dec 28, 2010 1:30 pm

No, the effect of gravity or air on the armature is very small and negligible. In gravity less vacuum the armature will behave the same way as on Earth.

The mechanism of a generator has nothing to do with gravity or air. The armature does not stop becuase of gravity or friction. It stops because energy is being taken out by applying electric potential, which does not depend on gravity or presence of air.

User avatar
Moon
Site Admin
Posts:751
Joined:Tue Nov 02, 2010 7:52 pm
Location:Dhaka, Bangladesh
Contact:

Re: Questions

Unread post by Moon » Sun Jan 02, 2011 3:41 am

bidrohi wrote:If I rotate the armature, it will stop because of gravity and friction. If it is vacuum then there will be no friction because of no air (except the friction in the parts), and by defying gravity the armature should rotate forever according to Newton's 1st law.
I would like to clarify a bit more. First of all, considering the conservation of energy law to be true, you can only get at most as much power as you give as input. The armature might move forever if there is NO magnetic field. However, to produce power you need to induce current, in that case you'll need magnetic field. But according to lenz law the armature won't move forever, because the induced current will thwart the movement of the armature.

http://en.wikipedia.org/wiki/Lenz%27s_law
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

Please install LaTeX fonts in your PC for better looking equations,
learn how to write equations, and don't forget to read Forum Guide and Rules.

User avatar
Zzzz
Posts:172
Joined:Tue Dec 07, 2010 6:28 am
Location:22° 48' 0" N / 89° 33' 0" E

Re: Questions

Unread post by Zzzz » Sun Jan 02, 2011 7:52 am

bidrohi wrote:... by defying gravity the armature should rotate forever according to Newton's 1st law.
এখানে একটু বোঝার ভুল আছে বলে মনে হইল :roll: নিউটনের ১ম সূত্র অনুসারে বল প্রয়োগ না করলে বেগ অপরিবর্তিত থাকবে। তারমানে এই না যে একটা বস্তুর উপর কোন রকম বল প্রয়োগ না করলে তা 'rotate' করতেই থাকবে। কোন কিছু বৃত্তাকার পথে ঘুরতে থাকলে তার বেগের পরিবর্তন হয় (দ্রুতির পরিবর্তন না হইতে পারে)। কারণ বেগ দিকের উপর নির্ভরশীল। সুতরাং সমদ্রুতিতে ঘুরলেও দিকের পরিবর্তনে বেগের পরিবর্তন হচ্ছে, এবং সেই বেগ পরিবর্তনের জন্য নিউটনের ১ম সূত্রানুসারে বল প্রয়োগ করতে হবে।
Every logical solution to a problem has its own beauty.
(Important: Please make sure that you have read about the Rules, Posting Permissions and Forum Language)

Post Reply