# How can you calculate change in magnetic flux?

by michaelw
Tags: flux, magnetic
 P: 80 Here is the problem A long and narrow rectangular loop of wire is moving toward the bottom of the page with a speed of 0.020m/s (see the drawing). The loop is leaving a region in which a 2.4-T magnetic field exists; the magnetic field outside this region is zero. During a time of 2.0s, what is the magnitude of the change in the magnetic flux? Please help me.. how do I do this? Attached Thumbnails
 P: 40 Since the magnetic flux is completely perpendicular to the loop, the magnetic flux at anytime is B*A, where A is only the area that is within the magnetic field. Magnetic flux = B*A you can differentiate this equation with respect to time to find the rate of change of flux, and relate dA/dt to the information given in the question. Because you are looking for the change only, you do not need to the know the total area, or the length, of the loop.
 P: 80 is there a way to do it without involving calculus :)?
HW Helper
P: 11,833

## How can you calculate change in magnetic flux?

You can do it,if the velocity is constant...(I think it is).

So yes.

$$\Delta \Phi =B \Delta A$$

What is the variation of the area...?

Daniel.
 P: 80 thanks :) are the units for magnetic flux Tm^2 (the SI unit)
 Sci Advisor HW Helper P: 11,833 1 Tm^2 is equal to one 1 Weber. Daniel.

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