<h3><u>Answer;</u></h3>
C. 12 units
<h3><u>Explanation;</u></h3>
- If the strength of the magnetic field at B is 3 units, the strength of the magnetic field at A is 12 units
- Magnetic field strength is one of two ways that the intensity of a magnetic field can be expressed.
- <em><u>The strength of the field is inversely proportional to the square of the distance from the source. This means that If the distance between two points in magnetic filed is doubled the magnetic force between them will fall to a quarter of the initial value. </u></em>
- <em><u>On the other hand, if the distance between two magnets is halved the magnetic force between them will increase to four times the initial value.</u></em>
The question involves a ping-pong ball that is held submerged in a bucket by a string attached to the bottom of the bucket.
The answer is the tension of the string will increase. This is because making the water salty increases its density, and consequently, increases its buoyancy. This is why sea water is more buoyant than fresh water. Therefore the ping pong is pushed more upwards by the water when salt is added than initially. This gives the string more tension.
Achieve a full outer shell
It's highly reactive and contains only one valence electron