Which of the following would increase the strength of an electromagnet?
check all that apply.
a. increasing the current flow
b. putting a piece of iron inside the loops of wire
c. increasing the number of loops of wire
d. spinning the loops
e. straightening the wire

A. Increasing the current flow

B. Putting a piece of iron inside the loops of wire

C. Increasing the number of loops of wire

Explanation:  An electromagnet is a device which has conducting wire coiled around a piece of metal usually an iron core. The metal acts as a magnet when current passes through the wire. The strength of the magnetic field depends upon the amount of current and number of loops of the coiled wire. Thus, if a piece of iron is placed inside the loops of wire, current is increased and number of loops is increased, the magnetic field strength increases.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.