Magnetic Flux Through a Square Loop

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The discussion revolves around calculating the magnetic flux through a square loop of wire with a given side length and angle to a magnetic field. The correct formula for magnetic flux is Φ = BAcosθ, where θ represents the angle between the normal to the loop and the magnetic field, not the angle the loop itself makes with the field. A common misconception is that the angle provided in the problem statement directly corresponds to θ in the formula. The participants clarify that if the angle were 90 degrees, the flux would be zero, as no magnetic field lines would pass through the loop. Ultimately, understanding the correct interpretation of θ is crucial for accurately calculating magnetic flux.
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Homework Statement


A loop of wire in the form of a square 1.50 m on each side, its plane makes an angle of 40.0° with a uniform magnetic field of 0.95 T. What is the magnetic flux through the loop?

Homework Equations


Φ = BAcosθ
A = s^2

The Attempt at a Solution


I found the area of the square using A = s^2 which returns 2.25m. Then I just plugged in the values provided in the question making sure to use 40°. I got Φ = 1.64Wb but the answer is 1.37Wb
 
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In the formula Φ = BAcosθ, can you describe in words the meaning of the angle θ? What particular angle does it represent?

The angle of 40.0° given in the statement of the problem might not be the angle represented by θ in the formula.
 
TSny said:
In the formula Φ = BAcosθ, can you describe in words the meaning of the angle θ? What particular angle does it represent?

The angle of 40.0° given in the statement of the problem might not be the angle represented by θ in the formula.
The angle in the formula is the angle the loop makes with respect to the magnetic field. If the angle was 90 the the magnetic flux would be zero because no magnetic field lines would pass through the loop.
 
ilovejava said:
The angle in the formula is the angle the loop makes with respect to the magnetic field. If the angle was 90 the the magnetic flux would be zero because no magnetic field lines would pass through the loop.
θ is not the angle that the plane of the loop makes to the magnetic field.

The picture below shows the case where the plane of the loop makes a 90o angle to the B field.
upload_2017-3-4_17-30-52.png

Would you say that the flux through the loop is zero here?
 
TSny said:
θ is not the angle that the plane of the loop makes to the magnetic field.

The picture below shows the case where the plane of the loop makes a 90o angle to the B field.
View attachment 114102
Would you say that the flux through the loop is zero here?
No the flux through the loop is not zero. I guess it's the angle made between the normal of the loop and the magnetic field?
 
ilovejava said:
No the flux through the loop is not zero. I guess it's the angle made between the normal of the loop and the magnetic field?
Yes, θ in the formula is the angle between the normal of the loop and the magnetic field.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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