# Physics

An infinite straight wire carrying a current I=5 A flowing to the right is placed above a rectangular loop of wire with width w=11 cm and length L=27 cm, as shown in the figure below. The distance from the infinite wire to the closest side of the rectangle is h=1.7 cm. The loop of wire has resistance R=0.31 Ohm.

(a) What is the magnitude (in Tesla) of the magnetic field due to the infinite wire at the point P in the rectangular loop, a distance r=3.2 cm from the wire (see figure).

In which direction does it point?

(b) Calculate the magnitude of the magnetic flux (in Tesla  m2) through the rectangular loop due to the magnetic field created by the infinite wire.

(c) Suppose the current in the infinite wire starts increasing in time according to I=bt, with b=50 Amps/sec. What is the magnitude (in Amps) of the induced current in the loop? Neglect any contribution to the magnetic flux through the loop due to the magnetic field created by the induced current.

(d) What is the direction of this current flow?

1. 1
1. a) B = mu_0*I/(2*Pi*r)

b) phi = (mu_0*I*L/(2*Pi))*ln(1+w/h)

c) i = (-1/R)*(mu_0*L)/(2*Pi)*ln(1+w/h)*(di/dt)

posted by ^_ ^
2. What is di/dt ??

posted by Phy
3. Phy, it's the b in the variation I=bt. Just use the b value in the problem for (di/dt)

posted by Anonymous
4. Thanks, can u tell me the solutions of 1,4,6,9,10,11,12?

posted by Phy
5. the C is wrong for me using the b in di/dt

posted by dd
6. Have you guys gt 3,5,7,8,9,10,11,12...????? Let's help each other and get this done guys!!

posted by robbo
7. C is wrong ...

posted by Sat
8. Some people haven't done even one question.

posted by boss
9. I wonder if some people understand the subject at all. It is an insult to the lecturer.

posted by boss
10. Hey boss, how did u come across this topic if you have not googled the question? It's obvious that you cheat also!

BTW - for C just use the value for b (the one in the question) b=(di/dt)

posted by Sat
11. Hey guys, what abput prob. 10?

posted by Anonymous
12. 10, b) how to solve

posted by BG

posted by Jack

posted by robbo
Q3 a=0 last part =0

posted by P
16. Anyone, can help with questions:

11 c)
10 b)
8 d,e,f)
5 b,d,e)

posted by BG
17. 11 a)
q/(4*pi*E_0*(r^2)*k)

11 b)
q*k/(r^2)

11 d) 0

posted by BG
18. anyone for question 7 please

posted by me
19. Hi BG, can you put the results for 8 a, b,c?

posted by Jack

posted by AAA
21. anyone for question 3 please??????

posted by AAA
22. 5 e)
v= m*g*R/(B^2*W^2)

posted by Jack
23. 8 a)
E = (st)/(S*E_0)
S = Area

8 b) E*d

8 c)
C = E*E_0*S/d

posted by BG
24. S = pi(b^2 - a^2)

posted by BG
25. Jack, did you solve anything else from this list:
11 c)
10 b)
8 d,e,f)
5 b,d)

posted by BG
26. me, I will exchange solution 8 on 7)

posted by BG
27. me, a = lambda/0.5
d = lambda/0.125

posted by BG
28. denaminator may be different, it depends on drawing

posted by BG
29. How I can know my denominator watching my grahp BG?

posted by AAA
30. prob 8

posted by BG
31. I think drawings at all identical so don't worry

posted by BG
32. BG sorry don't have 8 yet, i'll post it as soon as i solve it and thanks for 7

posted by me
33. i have 5 do you still need 5b and 5d

posted by me
34. BG,

8 d)

B= mu_0*(r^2-a^2)*s/(2*r*pi*(b^2-a^2))

posted by Jack
35. BG, do you have 10 c and d?

posted by Jack

posted by AAA
37. 8 e)
t*s^2/2*PI^2*(b^2-a^2)

posted by OVNI
38. 5) a)=B(l-W)z(t)
b)=(B*V*W)/R
c)=(B^2*V*W^2)/R
d)= (M*g*R)/(B^2*W^2)

posted by me

posted by Jack
40. 8 f)
Result of e multiplied by 2*pi*b*d

posted by Jack
41. i'm conufsed about the parentheses that might havve been omitted in OVNI's answer to 8e....

t*s^2/(2*PI^2*(b^2-a^2) )

Is this correct?

posted by robbo
42. I think a b is missing!

t*s^2/(2*PI^2*b*(b^2-a^2) )

posted by Jack
43. Sorry, it's

(t*s^2)/(2*PI^2*b*(b^2-a^2))

posted by OVNI
44. 8f, 8e solutions aren't working out as given by OVNI and Jack... help guys?

posted by robbo
45. Please 11 c) and 10!

posted by Jack
46. Jack, 11c is 0.5*L*I^2

posted by robbo
47. Thank you so much!
Question 10??

posted by AAA
48. Sorry, but I posted as I worked and I got a green check mark.
Please any one 9 and 10

posted by OVNI
49. Sorry I meant 10c is 0.5*L*I^2.... the LC circuit sum, does anybody have 10 b and d??

posted by robbo
50. how do you get 11 b and c???

posted by robbo
51. Roboo, why in your 11c you use L, and I?????

posted by OVNI
52. I meant 10c OVNI! Mistake... SOrry!

posted by robbo

posted by OVNI
54. 9b????

posted by robbo
55. robbo, the same that 9 a)

posted by Jack
56. 9b = 9a, E1 = V/d1 and E2 = V/d2

9c)try with charge conservation

posted by 124
57. robbo 10 b)

posted by Jack
58. 11 b)
q*9*(10^9)/r^2
r = distance from the origin

posted by BG
59. 10 b) 10 d) and 11 c) please!!!!

posted by Jack
60. 5A doesn't seem to work

posted by w
61. Please give ans for Q5 for values I am getting them last chance please

What is the total magnetic flux through the loop (in Tesla m ) when is 62 cm. Include only the magnetic flux associated with the external field (i.e. ignore the flux associated with the magnetic self-field generated by the current in the wire loop). Note that you do not need to calculate or know at what time the loop is at this location.

incorrect

(b) Using Faraday's Law and Ohm's Law, find the magnitude (in Amps) of the induced current in the bar at the time when 1.00 m/sec. Note that you do not need to calculate or know at what time the loop has this speed.

incorrect

(c) Which way does the current flow around the loop, clockwise or counterclockwise?

Status: correct

(d) What is the total magnetic force (in Newtons) on the rigid wire loop when 1.00 m/sec? Again, ignore any effects due to the self magnetic field.

direction:
Status: correct

magnitude (in Newtons):

incorrect

(e) What is the magnitude of the terminal speed (in m/sec) of the loop (i.e. the speed at which the loop will be moving when it no longer accelerates)?

posted by P
62. 8 e)

poling vector = E*B/mu_0 = ??

posted by BG
63. it's correct ?

posted by BG
64. P, phi=B*w*(L-z)
|em|=|dphi/dt|=B*w*V
i=|em|/R=B*w*V/R
F=watt/ms^-1=(|em|^2/R)*1/V

posted by 124
65. BG, OK

posted by 124

posted by Jack
67. 10b)= frequency that abs(i(t))=max

posted by 124
68. f= 1/(2*pi*sqrt(L*C))?

posted by Jack

posted by Jack
70. i(t)=I0*cos(w*t) and abs(i(t))=max if
w*t=k*pi, for k=1=>t1=pi/w
f=1/t1=w/pi=1/(pi*sqrt(L*C))

posted by 124
71. 124, i have E and B correct
but

pointing vector with formula E*B/mu_0, mu_0 = 4*pi*10^(-7), incorrect.

pliz, tell where is error?

posted by BG
72. 10d)=>average p=v*i on [0,3*t1]

posted by 124
73. BG, S=E*B/mu_0
= 1/(2*pi^2*b)*s^2*t/(b^2-a^2)

posted by 124
74. 10b) f=1/t1=w/pi=1/(pi*sqrt(L*C))

posted by 124
75. BG, B(r=b) = mu_0*s/(2*pi*b)is not the the previous B(r)

posted by 124
76. 124, thanks a lot, you the man. )

posted by BG

posted by BG

posted by Jack
79. in 10d for P=V*I, where do we get V from???

posted by robbo
80. robbo, v=Ldi/dt
P_mean=1/(3T-0)*int(v*i,0,3*T)
T=2*pi*sqrt(L*C)

11c)e)=>Q_net+ q = Q_encl in the gauss Law

posted by 124
81. S=E*B/mu_0
= 1/(2*pi^2*b)*(s^2)*(t/(b^2-a^2))

What's wrong with this formula guys??

posted by robbo
82. (t*s^2)/(2*(PI^2)*b*(b^2-a^2))

posted by Jack
83. robbo, formula is right, check s^2*t
for example s=24u and t=5u
s^2*t = 24*24*5*1u^3

posted by 124
84. 10 d) Positive or negative?

posted by Jack
85. Is this correct for 10 d)=

P=1/3T * int(-L*w*(Imax)^2*sin(wt)*cos(wt), 0 , 3T)
Thanks!!!

posted by Jack
86. Jack, and 124, for the formula:(t*s^2)/(2*(PI^2)*b*(b^2-a^2)) = 5.27300181668e-11

at s=12uC/sec, t=1usec, b=0.0053m, a=0.0014m

I've followed the formula, but the answer shows wrong... I hope you guys can help?

posted by robbo
87. Jack, the formula you've used is correct :)

posted by robbo
88. Q11 formulae, anybody??

posted by robbo
89. Jack, yes the formula is OK

posted by 124
90. 124, I have no idea what on earth I'm doing wrong, followed your formula... and input values and got the same answer everytime I tried, apparently its incorrect! :( Can you input my values and see what answer you get?

posted by robbo
91. robbo,sorry i forgot e_0
(1u*12u^2)/(2*(PI^2)*5.3m*(5.3m^2-1.4m^2)*8.85e-12) =5.95215457341
E =|E|er
|E|=1/(4*pi*e_0*kappa)*q/r^2 for (a<r<b) |E|=1/(4*pi*e_0)*q/r^2 for r>=b

posted by 124
92. S=E*B/mu_0
= 1/(2*pi^2*b*epsilon_0)*(s^2)*(t/(b^2-a^2))

posted by 124
93. guys, you can subscribe in the new course ReView (8.MReVx)

posted by 124
94. 10d)
P=1/3T * int(-L*w*(Imax)^2*sin(wt)*cos(wt), 0 , 3T) = 0!!!!!

T=2*pi*sqrt(L*C)

posted by 124
95. 124, i think its supposed to be t^2/(b^2-a^2) instead of t to the power of 1.

posted by robbo
96. 9c, 11c anybody?

posted by robbo
97. 11 c) Is the net charge positive or negative?

posted by Jack
98. THIS IS CHEATING!!! YOU ARE NOT FOLLOWING THE HONOUR CODE!!

posted by MIT
99. Dear MIT, you got here by???? Googling for what?

posted by HarvardX

posted by l

posted by Jack
102. it seems that we cheated. So I leave. Good luck to all!

posted by 124

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