Better Students Ask More Questions.
How many excess electrons are on the negative cork and how many electrons has the...
How many excess electrons are on the negative cork and how many electrons has the positive cork lost? A small cork with an. . .
excess charge of +7.0 μC is placed 0.20 m from another cork, which carries a charge of −3.2 μC. The magnitude of the electric force is 5.033028 N. The Coulomb constant is 8.98755 × 109 N · m2/C2.
1 Answer | add yours
The net electric force between two charged objects in vacuum with charges `q1` and `q2` is given by the Coulomb law:
`F = (q1*q2)/(4*pi*epsilon0*R^2)`
where `R` is the distance between the two charges.
With the data in the text one has
`F = (7*10^-6*(-3.2*10^-6))/(4*pi*8.854*10^-12 *0.2^2) =-5.032 N`
The negative sign shows that the force is opposing the vector `R(=R_12) =R_2-R_1` drawn from first charge to the second charge and thus it is an attraction force.
Since the charge of an electron is `e =-1.6*10^-16 C` the number of electrons the positive cork lost is
`N_1 = q_1/|e| =(7*10^-6)/(1.6*10^-19) =4.375*10^13 "electrons"`
and the number of excess electrons the negative cork has is
`N_2 = q_2/e =(-3.7*10^-6)/(-1.6*10^-19) =2.3125*10^13 "electrons"`
Posted by valentin68 on October 16, 2013 at 1:26 PM (Answer #1)
Join to answer this question
Join a community of thousands of dedicated teachers and students.