The image shows an infrared picture of a disc brake on a car after it has been driven and stopped. heat is created when the brake pad comes in contact (rubbing) with the brake disc.
what causes the disc brake to heat up to almost 200°f ?
a)
bad tires
b)
friction
c)
solar energy
d)
electromagnetic energy

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.