Question

The ratio of electrostatic to gravitational force between two electrons place at certain distance in air is

Answer 1

The magnitudes of the gravitational and electrostatic force are given by,

FG=Gm1m2r2

FE=kq1q2r2

So, the ratio is,

FGFE=Gm2eke2

Where the 1/r2 have cancelled.

Now, we use the values:

G=6.67×10−11 N-m2kg−2

me=9.1×10−31 kg

k=9×109 N-m2 C−2

e=1.6×10−19 C

FGFE=(6.67×10−11)(9.1×10−31)2(9×109)(1.67×10−19)2=2.4×10−43