# Lenz Law - sinusoidal current

I am trying to understand something about Lenz law. First, let me show an example of what I do understand.

In this image, I understand

• a) As the loop moves closer to the current the field increases. So therefore the current must go in the opposite direction, thus counter clockwise.

• b) the loop moves farther away, the field decreases, so the current moves clockwise around the loop.

• c) the field doesn't change, so there is no current change.

• d) the current increases, which increases the field, and that has to be negated, so counter clockwise.

Those are the correct answers.

However, when looking at another example, I am having some troubles.

With this I understand b) and c).

• b) The current is constant, no change.

• c) Again, there current is constant, and the loop is not moving in a way to change the field.

But for a) and d). I don't understand.

• a) is clockwise, so this is acting a decrease.
• d) is counter clockwise, so this is acting as an increase.

But I don't understand how the sinusoidal are interacting differently. Can someone please explain how the sin and cos functions act on the loop?

Thanks!

Using V = N$\dfrac{d\Phi}{dt}$ we can predict what the phase angle is of the driving voltage that is induced into the loop by the changing magnetic field.
This means that $V_{INDUCED}$ is leading the sinewave current by 90 degrees.