Questions bugging me in magnetism and diodes

• WoAiMeiMei

  8 Apr 09, 20:52

  

   

  Solved

   

  Crimson soldier's solution:

  Part 1) The magnetic flux forms a closed loop through the iron core and air-gap. flux density through a1= 10/18 * 1.7T = ...

  part 2) mmf = total magnetic flux * reluctance = (answer from part 1) * (area a1) * ( 0.135)/(3100* permeability of vacuum *area a1)=...

  part 3) repeat part 2 with different length and different flux density and different area

  part 4) repeat part 2 with different length, flux density, area, and permeability

  part 5) sum up the magneto-motive force and use mmf= N* I

• charlize

  8 Apr 09, 20:55

  Basket.

   

  Where got easy?

• WoAiMeiMei

  8 Apr 09, 20:57

  lol :/

• gunner77

  8 Apr 09, 20:58

  fk la

  so hard

• charlize

  8 Apr 09, 21:00

  You think sgforums populated by PhD holders in engineering ah?

• sinicker

  8 Apr 09, 21:03

  wah! i study uni also dono lehs!
  
  ps : no lah i typing one hand, eat magnum icecream w/ the other.

• WoAiMeiMei

  8 Apr 09, 21:27

  Eagle has the skills but he's likely to be busy

• SBS2601D

  8 Apr 09, 21:29

  These should be standard A lvl Physics question.

  Dio boh?

  I can't really recall.

• eagle

  8 Apr 09, 22:30

  I do one question first

   

  

  We need to use kirchoff current's law

  Let current through Vs = I1 (rightwards)
  Let current through resistor R1 = I2 (downwards)

  a) take one round around the left half

  9 = (I1)(800) + (I2)(400)
  800 I1 + 400 I2 = 9 -- (1)

  Take the round around big rectangle

  9 - 0.7 - 0.7 = (I1)(800) + (Id)(800)
  800 I1 + 800 Id = 7.6 -- (2)

   

  Finally, we know total current entering a junction = total current exiting a junction, so
  I1 = I2 + Id

  
  Solve simultaneous equations of 3 variables

  I1 = 8 mA
  I2 = 6.5 mA
  Id = 1.5 mA

   

  Try repeating my method for part b

   

  I look at the rest when got time

• eagle

  8 Apr 09, 22:31

  Originally posted by sinicker:

  wah! i study uni also dono lehs!
  
  ps : no lah i typing one hand, eat magnum icecream w/ the other.

  I also forgot a ton of uni stuff already :( :(

• WoAiMeiMei

  10 Apr 09, 14:55

  electricity is annoying ;/

• WoAiMeiMei

  11 Apr 09, 18:06

  help .. :/

• charlize

  11 Apr 09, 18:47

  Originally posted by WoAiMeiMei:

  electricity is annoying ;/

  Can't live with them.

   

  Can't live without them.

• WoAiMeiMei

  12 Apr 09, 09:23

  the last question of the last pic is really bugging me =.=

• WoAiMeiMei

  13 Apr 09, 13:15

  ive solved all buy the magnetism q.

   

  working on it now

• WoAiMeiMei

  13 Apr 09, 21:32

  no Luck :x

• crimson soldier

  13 Apr 09, 22:20

  Lol where this question from? Are you from NTu engineering taking physics?

  I've not learnt this yet but I can try to solve it using what ive learnt in maxwell's equations ...lol

  Part 1) The magnetic flux forms a closed loop through the iron core and air-gap. flux density through a1= 10/18 * 1.7T = ...

  part 2) mmf = total magnetic flux * reluctance = (answer from part 1) * (area a1) * ( 0.135)/(3100* permeability of vacuum *area a1)=...

  part 3) repeat part 2 with different length and different flux density and different area

  part 4) repeat part 2 with different length, flux density, area, and permeability

  part 5) sum up the magneto-motive force and use mmf= N* I

• Doraemonboi

  13 Apr 09, 22:21

  I DON"T UNDERSTAND !@#!@$% T_T so chim

• WoAiMeiMei

  14 Apr 09, 15:13

  Ill have to come back to that problem later tonight.. :x

  and nah, im actually studying in an overseas university

• WoAiMeiMei

  14 Apr 09, 21:04

  Anyways, thanks guys for your help :P managed to correct my problems

• crimson soldier

  15 Apr 09, 00:23

  good luck!

  richard feynman - 'Physics is like sex. Sure, it may give some practical results, but that's not why we do it.'