I’m a senior in high school and I don’t know how to choose sin or cos in physics problem. For the most part I memorised them. For example, why is the flux of a magnetic field = BAcos(angle) and why is the electromagnetic force = ILBsin(angle).
The last two years weren’t normal as we studied online so it’s highly appreciated if someone can eli5 and fill in the gaps for me.
In: 4
The easy way to remember is to imagine what you’d expect if the angle were 0 and what you’d expect if it were 90.
Sin(0) = 0, Sin (90) = 1
Cos(0) = 1, Cos(90) = 0
The amount of flux is based on the field going _through_ the surface. Remember that the vector associated with the surface is perpendicular to the actual surface. So when the angle between A and B is zero, the surface is completely perpendicular to the field, so that is when the flux is at its maximum. When the angle between A and B is 90 degrees, that means the surface is parallel to the field, and none of the field goes through the surface.
So flux is a maximum at 0 degrees, and minimum at 90. So you use Cosine.
For electromagnetic force, it’s the opposite. The most force happens when the angle is 90, and there’s no force when the charge is moving parallel to the field. So maximum at 90, minimum at 0 – use Sine.
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