Calculating Charge, Current, and EMF in a Reversing Magnetic Field"

[Seiya]

Hey lads, if anyone can, please check If I am correct... Thanks :)

A 100 turn circular coil has a diameter of 2 cm and a resistance of 50 Ohms. The plane of the coil is perpendicular to a uniform magnetic field of magnitude 1 T. The direction of the field is suddenly reversed.

(a) Find the total charge that passes through the coil. If the reversal takes 0.1 s, find
(b) the average current in the coil and
(c) the average emf in the coil


So I got...

I= dq/dt

Е=-dф/dt

Edt/R=dQ

Integral of dQ = Q = -1/R (int from ф0 to фf) dф

= -1/R(фf-ф0) = -(delta)ф/R

ф0 (field goes inside, n vector goes inside) = NBAcos() = +NBA
фf (field goes outside, n vector goes inside) = NBAcos() = -NBA

So Q = - (-NBA-(NBA))/R = 2NBA/R = .001256C

(b) I = dQ/dt and dt= .1s
= .01256A (since dQ = Q because Q0= 0 )

(c) E=IR = 0.626V

Am I correct? If not can you please point out any mistakes I have made... thanks i very much appreciate it =)

 

[nrqed]

Hey lads, if anyone can, please check If I am correct... Thanks :)

A 100 turn circular coil has a diameter of 2 cm and a resistance of 50 Ohms. The plane of the coil is perpendicular to a uniform magnetic field of magnitude 1 T. The direction of the field is suddenly reversed.

(a) Find the total charge that passes through the coil. If the reversal takes 0.1 s, find
(b) the average current in the coil and
(c) the average emf in the coil


So I got...

I= dq/dt

Е=-dф/dt

Edt/R=dQ

Integral of dQ = Q = -1/R (int from ф0 to фf) dф

= -1/R(фf-ф0) = -(delta)ф/R

ф0 (field goes inside, n vector goes inside) = NBAcos() = +NBA
фf (field goes outside, n vector goes inside) = NBAcos() = -NBA

So Q = - (-NBA-(NBA))/R = 2NBA/R = .001256C

(b) I = dQ/dt and dt= .1s
= .01256A (since dQ = Q because Q0= 0 )

(c) E=IR = 0.626V

Am I correct? If not can you please point out any mistakes I have made... thanks i very much appreciate it =)

This looks completely right to me.

 

[kyle8921]

Hello! Your calculations seem to be correct. However, I would like to clarify a few points. Firstly, in part (b), you have correctly calculated the average current to be 0.01256A, but this is only the average current during the reversal period of 0.1s. If you want to find the overall average current in the coil, you would need to take into account the initial current before the reversal as well.

Secondly, in part (c), you have correctly calculated the average emf to be 0.626V. However, this is the average emf during the reversal period of 0.1s. If you want to find the overall average emf in the coil, you would need to take into account the initial emf before the reversal as well.

Overall, your calculations seem to be correct and you have a good understanding of the concepts involved. Keep up the good work!