3. When does the iron core in an electromagnet become magnetic?

When electricity flows through it.

Explanation:

The electromagnet exhibits magnetic properties only as soon as current flows through the nucleus. Namely, the electric current in the space around the electrical conductor through which it passes creates a magnetic field. Unlike a permanent magnet, which has a permanent property of magnetism, the electromagnet is a temporary magnet because the magnetic field also disappears when the current ceases.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2