Three equal charges of magnitude 'e' are located at the vertices of an equilateral triangle of side 1m. where should you place a charge of 2e' so that the '2e' does not experience any force?

At centroid

Explanation:

In the given equilateral triangle ABC with side of 1 m. The three equal charges e,e,e are placed at the A,B and C.

And the fourth charge 2e is put at point O which is called centroid.

Now we can calculate the distance AD by applying pythagorean theorem as,

Put the values and get.

Now calculate AO as,

And the sides BO=CO=AO.

Now Force can be calculated as

And similarly,

Now we can calculate resultant of in upward direction. as,

Therefore the resultant force on centroid O.

Therefore the fourth charge 2e should be placed on centroid so that it experience zero force.

their crystal patterns have been disrupted by stress

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.