The EMF does not depend on which of the following? A. The magnetic field strength
B. The number of electrons in the magnetic field
C. The velocity of the wire in the field
D. The length of the wire in the magnetic field

Explanation:

When a wire of length L is moved with velocity v , perpendicular to magnetic field B , EMF will be produced at its two ends . EMF can be calculated with the help of following expression

EMF = BLv

As per this formula , EMF produced will not depend upon number of electrons in the magnetic field.

So B is the right choice.

the independent variable, or the one that is intentionally manipulated is the speed.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.