Identify the materials necessary to create an electromagnet. a: power source, metallic core, and electrical conductor. b: electrical conductor and power source only. c: metallic core, magnet, and power source. d: metallic core and power source only. i appreciate it.

The correct answer is "Power source, metallic core, and electrical conductor".

Explanation:

Electromagnet: It is a temporary magnet. It consists of wrapping coils around iron core and the power source. When the current passes through the coils around the iron core then it will get magnetized. The domains of the electromagnet gets aligned.

As long as the current passes through it, it will get magnetized. It will loose its magnetism easily when the power is switched off.

In the electromagnet, the strength of the magnetism can be increased or decreased. The poles of the electromagnet are not fixed.

Therefore, the correct option is (A).

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answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.