Question

The separation between two magnets is reduced by a factor of 5. How does the force between them change?

Question 18 options:

increases by a factor of 5


increases by a factor of 25


decreases by a factor of 5


decreases by a factor of 25


doesn't change

Answer 1

Answer:Increase by a factor of 25

Step-by-step explanation:

We know that magnetic force is proportional to
`(1)/(r^2)`

where r is the distance between them

`F\propto B\propto (1)/(r^2)`

Thus
`F\propto (1)/(r^2)`

Where
`B`=magnetic field

If distance is reduced by a factor of
`5` then force must increase by a factor of
`25` because

`r\rightarrow (r)/(5)`

so
`F\propto (1)/(((r)/(5))^2)`

`F\propto (25)/(r^2)`