Rate of Change of Magnetic Field in Square wire loop

In summary: If the magnetic field were zero, the current would be in the same direction as the magnetic field. That means the current in the circuit would be increasing. Conversely, if the magnetic field were constant, the current would be in the opposite direction of the magnetic field. So the magnitude of the magnetic field would be decreasing.
  • #1
CDreyer23
3
0

Homework Statement



The circuit shown is in a uniform magnetic field that is into the page. The total current in the circuit is 0.20 A, flowing counterclockwise. At what rate is the magnitude of the magnetic field changing? Is it increasing or decreasing?
Square wire loop with base and height of 12 cm
One 4 V battery and one 10 Ω resistor

Homework Equations

(first ever post so sorry for the poor formatting)[/B]
dB = (μ0 * (I*ds)x(r))/(4πr2)
Bloop = (μ0*I)/(2r)

The Attempt at a Solution


Given the direction of the current and using the right hand rule, the magnetic field produced by the current opposes the uniform one into the page, so it's magnitude is decreasing. However, the given equations don't fit with a square loop. I initially tried the second equation, but since r is changing it didn't work. I'm assuming the first equation is the one that's needed since we're looking for the change in magnetic field but I can't seem to find what ds should be.

Thanks for the help!
 
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  • #2
There is no circuit shown. Can you post a figure?
 
  • #3
kuruman said:
There is no circuit shown. Can you post a figure?
I'm not sure how to add a photo or a figure since there is no picture online it's on my professor's sample final exam. It is a square loop with side length of 12 cm. There is a 4V battery on the bottom and a 10 Ω resistor connected in series at the top. Current is moving counterclockwise, hope this is enough info to help
 
  • #4
Sometimes people post pictures that they take with their phones. If you do that, be sure everything is legible. It is not clear from your description why there should be a changing magnetic field.
 
  • #5
AK95wyC.png

The answer key says the correct answer is C
 

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  • #6
Great, thanks. Your posted equations are not relevant to this problem. This question has to do with Faraday's law not Biot-Savart. First, ask yourself what the current in the circuit would be if the magnetic field into the page were constant or even zero.
 

What is the rate of change of magnetic field in a square wire loop?

The rate of change of magnetic field in a square wire loop refers to the change in the strength or direction of the magnetic field over a certain period of time. In other words, it measures how quickly the magnetic field is changing.

How is the rate of change of magnetic field in a square wire loop calculated?

The rate of change of magnetic field in a square wire loop can be calculated using the formula: dΦ/dt = -BAcosθ, where dΦ/dt is the rate of change of magnetic flux, B is the magnetic field strength, A is the area of the loop, and θ is the angle between the magnetic field and the normal to the loop.

What factors can affect the rate of change of magnetic field in a square wire loop?

The rate of change of magnetic field in a square wire loop can be affected by various factors such as the strength and direction of the magnetic field, the size and shape of the loop, the material of the wire, and the speed and location of the loop.

Why is the rate of change of magnetic field important?

The rate of change of magnetic field is important because it is a key factor in determining the induced voltage in a wire loop. It is also used in many applications such as generators, transformers, and electric motors.

How is the rate of change of magnetic field related to Faraday's Law?

The rate of change of magnetic field is directly related to Faraday's Law which states that the induced electromotive force (EMF) in a closed loop is proportional to the rate of change of magnetic flux through the loop. This means that a larger rate of change of magnetic field will result in a larger induced EMF.

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