Abar magnet is a permanent magnet, while an electromagnet is a temporary magnet. why is an electromagnet temporary?

An object that possesses a magnetic field and exerts a type of magnetic force are called a magnet.  Magnets can be temporary or permanent based on their properties.

The difference between the magnet is due to the current.

The flow of an electric current produces an electromagnet, the electromagnet remains working only when the current is flowing, when the current is turned off, the electromagnet loses its properties.

The material, coiling and the amount of current determine the nature of the electromagnet. While bar magnets are small magnets used for attracting metallic objects.

Therefore, an electromagnetic field relies on the potential of an electric field.

Learn more about magnets here:

link

The magnetic field of electromagnets depend on current

Explanation:

An electromagnet is a temporary magnet because it do no have any inbuilt source of magnetism. The electricity flowing through it produces magnetic force  and as soon as this electric force is removed , the magnetic force also vanishes.

Thus, the magnetic field of electromagnet depends on the potential for an electric field.

Wherever there is electricity, there is a magnetic field, and wherever there is magnetism, there is potential for an electric field.

1. (1.2kw)x(15/60hours) = .3kwh --> a

2. (5kw)x(90/60hours)x(8cents/kwh) = $0.60 --> d

3. microwave --> 1200 watts = (1.2kw)x(6/60hours) = .12kwh

coffee-maker --> 900 watts = (.9kw)x(10/60hours) = .15kwh

therefore, it requires more energy for the coffee-maker to do the same amount of work.

so the answer is a.