1. Electric Fields

2. Mass distorts the space-time around it creating a gravitational field of different strengths depending how far you are away from the mass.

3. Electric charges do the same thing
Electric charges do the same thing. An electric field is created around the charge, whose strength is defined as:
Charge of small, + test charge
The units would be N/C

4. Electric field strength can also be related in terms of charge and distance from that charge:
Amount of charge
Electric field strength
Distance2 from charge
Coulomb’s Constant

5. In talking about an electric field, you decide what a small, positive “test charge” would do, when talking about the direction of forces.

6. Electric field lines show the direction of force on a positive test charge
The concentration of field lines represents the strength
Field lines cannot cross

7. Find the Electric Field strength here
EB= kCq/r2
= (8.99 x 109 Nm2/C2)(8.9 x 10-6C)/(4m)2
= 5001 N/C
5001 N/C
EA = (8.99 x 109 Nm2/C2)(5.8 x 10-6C)/ (5m)2
EA = 2086 N/C
Resultant = ((5001 N/C)2 + (2086 N/C)2)-1/2
2086 N/C
= 5418 N/C
Direction = tan-1 (2086 N/C)/(5001 N/C) =
270° +
23°
= 293°

8. Equilibrium

9. Problem 1
An electron is suspended 10 m above another electron, and dropped. At what point will the dropped electron float motionless in space?
me = x kg
qe = 1.60 x C
Fg = FE
kC = 8.99 x 109 Nm2/C2
g = m/s2
= m

10. Problem 2
A charge of 3mC is 10m away from a charge of 7mC. Where would a charge of -5mC, placed between them, be motionless?
x = ?
q3 = -5 x 10-3 C
q2 = 7 x 10-3 C
q1 = 3 x 10-3 C
F13 = F23

12. = 3.95m