The force between them <em>decreases</em><em>,</em> as the square of the distance.
For example ...
-- If you move them apart to double the original distance, the force becomes (1/2²) = 1/4 of the original force.
-- If you move them apart to 3 times the original distance, the force becomes (1/3²) = 1/9 of the original force.
-- If you move them apart to 5 times the original distance, the force becomes (1/5²) = 1/25 of the original force.
(Gravity works exactly the same way.)
Answer:
B on edge
Explanation:
the piles of the magnetic field generated around the armature are attracted to the opposite poles of the permanent magnent. As the opposite poles align, the commutator reverses the current direction so like poles are aligned and the armature continues to spin
Answer:
- a change in color
- the formation of a precipitate
- the formation of bubbles
Explanation:
In a chemical reaction, there is always a rearrangement of atoms within the molecules of reactants to form new products. Such a change is different from changes in the physical form of molecules, e.g. shape.
Thus, according to this criteria, only three options are correct in the given question. A change in color is definitely an indication of chemical reaction because the emission of light before and after cannot be changed unless molecules are rearranged to form a new chemical. Likewise, precipitates form when a reaction takes place between chemically dissolved molecules to form less or not dissolvable compounds. In the end, the configuration of bubbles also indicates that the reaction has taken place because new gases are being released.
On the other hand, change in shape is a physical change because the composition doesn't need to also been changed. An example is the ice formation from water. Same is the case with "change of clear liquid to cloudy" because the addition of non-reactive substances could change the nature of liquid to cloudy however the reaction doesn't need to have taken place.
