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1. An electron and a proton have charges of an equal magnitude but opposite sign

ID: 2130536 • Letter: 1

Question

1. An electron and a proton have charges of an equal magnitude but opposite sign of 1.60 10-19 C. If the electron and proton in a hydrogen atom are separated by a distance of 8.00 10-11 m, what are the magnitude and direction of the electrostatic force exerted on the electron by the proton?

magnitude ________ N

direction--> attractive/repulsive??

______________________________________________________________________________________

2. A test charge of +8.00 10-6 C experiences a downward electrostatic force of 11 N when placed at a certain point in space. What are the magnitude and direction of the electric field at this point?


magnitude _______ N

direction up/down??

______________________________________________________________________________________

3. Two positive charges, each of magnitude 3. 10-6 C, are located a distance of 4 cm from each other.

(a) What is the magnitude of the force exerted on each charge?

_______ N

(b) On a drawing, indicate the directions of the forces acting on each charge.

______________________________________________________________________________________

4. A charge of -3.50 10-6 C is placed at a point in space where the electric field is directed toward the right and has a magnitude of 7.50 104 N/C. What are the magnitude and direction of the electrostatic force on this charge?


magnitude _______ N

direction right/up/left/down??

______________________________________________________________________________________

5. Two charged particles exert an electrostatic force of 5 N on each other. What will the magnitude of the electrostatic force be if the distance between the two charges is reduced to one-half of the original distance?

___________ N

_____________________________________________________________________________________

6. A charge of +5.00 10-6 C is located 11 cm from a charge of -4.00 10-6 C.

(a) What is the magnitude of the force exerted on each charge?

_________ N

(b) On a drawing, indicate the directions of the forces acting on each charge.

Explanation / Answer

1.the force is

F = k x (q1q2/r^2)

where k = (1/4pi x e_o) = 9 x 10^9 Nm^2/C^2,q1 = q2 = 1.6 x 10^-19 C and r = 8.00 x 10^-11 m

2.the test charge is q = +8.00 x 10^-6 C

the electrostatic force is F = 11 N

we know that

F = E x q

where E is electric field

or E = (F/q)

3.the charges are q1 = q2 = 3.0 x 10^-6 C

the distance between them is r = 4 cm = 4 x 10^-2 m

the force between them is

F = k x (q1q2/r^2)

the direction of the force is repulsive

4.the charge is q = -3.50 x 10^-6 C

the electric field is E = 7.50 x 10^4 N/C

the electrostatic force is

F = E x q

the direction of the force is towards left as the charge is negative

5.the force is proportional to square of inverse of distance,that is,

F1 = k x (1/r1^2)

where k is constant

similarly,

F2 = k x (1/r2^2)

or F2/F1 = (r1/r2)^2

or F2 = F1 x (r1/r2)^2

here,r2 = r1/2

or F2 = F1 x (2)^1/2 = 5 x (2)^1/2 N

6.the charges are q1 = +5.00 x 10^-6 C

and q2 = -4.00 x 10^-6 C

they are separated by distance r = 11 cm = 11 x 10^-2 m

the electrostatic force on each charge is

F = k x (q1q2/r^2)

the direction of the force is from charge q1 to charge q2(attractive force)