The electric field that is 0.25m from a small sphere is 450n/c toward the sphere. a. is the charge positive or negative? why? b. what is the magnitude of the charge on the sphere?

PART 1)

A small sphere is considered to be a point charge

So here if electric field is indicating the position of charge itself or it is towards the charge then it must be a negative charge on the sphere

PART 2)

Electric field due to a point charge is given by

here

= distance of charge from the point where field strength is required

= 0.25 m

now from the above equation we can say

So magnitude of charge is 3.125 nC on the small sphere

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.