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What is the equation for induced voltage, when everything is constant accept the magnetic field.

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What is the equation for induced voltage, when everything is constant accept the magnetic field.

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Doc Al

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ThatWhat is the equation for induced voltage, when everything is constant accept the magnetic field.

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A circular loop of radius 31 cm is located in the plane of the paper inside a homogeneous magnetic field of 0.3 T pointing into the paper. It is connected in series with a resistor of 289 Ω. The magnetic field is now increased at a constant rate by a factor of 2.4 in 13 s. Calculate the magnitude of the induced emf in the loop during that time.Thatisthe equation (Faraday's law). What is the exact problem?

I have been using Faraday's. So far Ive tried [(2.4-0.3)/13)*pi(.31)^2], [(2.4+0.3)/13)*A], and [(2.4/13)*A]. All in magnitude form.

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Doc Al

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What's theThe magnetic field is now increased at a constant rate bya factor of2.4 in 13 s.

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2.4-0.3=2.1What's theinitialmagnetic field before it starts increasing? What's thefinalmagnetic field after 13 seconds? The change in magnetic field during that time?

According to Faraday this divided by the time ,t=13s, all multiplied by the area, A=pi*(.31)^2, should equal the EMF but LON-CAPA does not agree.

Am I missing something? it seems pretty straight forward but it isn't coming out right. btw my answer was 0.0488V

- #6

Doc Al

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You are misreading the problem statement. 2.4 is not the final magnetic field, but the2.4-0.3=2.1

According to Faraday this divided by the time ,t=13s, all multiplied by the area, A=pi*(.31)^2, should equal the EMF but LON-CAPA does not agree.

Am I missing something? it seems pretty straight forward but it isn't coming out right. btw my answer was 0.0488V

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2.7 ill see if it worksyou are misreading the problem statement. 2.4 is not the final magnetic field, but thefactorby which the field is increasing. So once again: What's the final magnetic field after 13 seconds?

- #8

Doc Al

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No. Show how you made that calculation.2.7 ill see if it works

FYI: Factor means multiply. If you start out weighing 150 lbs and your weight increases by a factor of 2, what's your final weight?

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Ok that didnt work. So the way its worded it looks like the total time it takes to charge up 2.4 is 13s but I guess it could mean that it charges up 2.4 every second for 13s....Ill try itYou are misreading the problem statement. 2.4 is not the final magnetic field, but thefactorby which the field is increasing. So once again: What's the final magnetic field after 13 seconds?

- #10

Doc Al

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Nope. Reread my last comment.Ok that didnt work. So the way its worded it looks like the total time it takes to charge up 2.4 is 13s but I guess it could mean that it charges up 2.4 every second for 13s....Ill try it

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Ok so im going to multiply my initial 0.3 by a factor of 2.4?Nope. Reread my last comment.

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*over a time period of 13s

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Doc Al

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Yes. At least I hope so!Ok so im going to multiply my initial 0.3 by a factor of 2.4?

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nope

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- #16

Doc Al

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Nope what?nope

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That doesn't work.Nope what?

- #18

Doc Al

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Show what you did.That doesn't work.

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(2.4*0.3)/13)*pi*(.31)^2=0.0167VShow what you did.

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Doc Al

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You need the(2.4*0.3)/13)*pi*(.31)^2=0.0167V

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dB/dt=(2.4-0.3)/(13) ?You need thechangein magnetic field over time, not just the final field.

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or (2.4*0.3)-(0.3))/13

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Success! That problem had really sneaky wording.

- #24

Doc Al

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Finally!Success! That problem had really sneaky wording.

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"Calculate the average induced voltage when the magnetic field is constant at 0.72 T while the loop is pulled horizontally out of the magnetic field region in 4.1 s"