Explanation:
It is given that,
Mass of the object, m = 0.8 g = 0.0008 kg
Electric field, E = 534 N/C
Distance, s = 12 m
Time, t = 1.2 s
We need to find the acceleration of the object. It can be solved as :
m a = q E.......(1)
m = mass of electron
a = acceleration
q = charge on electron
"a" can be calculated using second equation of motion as :




a = 16.67 m/s²
Now put the value of a in equation (1) as :


q = 0.0000249 C
or

Hence, this is the required solution.
There is no equation here
Density can be any number, as long as it has the right units.
A unit of density has to be (a unit of mass) divided by (a unit of volume).
The most common one is gram/cm^3.
Scientific Notation: 4.580 x 10^-4
Scientific e Notation: 4.580e-4