1. Aim: How do we explain electric fields?

2. Electric Field Concept
All charges produce electric fields (just as all masses produce gravitational fields). Any charge placed in an electric field will experience an electrostatic force.

3. Electric Field Intensity
We can calculate the electric field intensity by placing a test charge in an electric field, measuring the electrostatic force acting on the test charge, and dividing the force by the magnitude of the test charge. E=F/q

4. Electric Field Intensity
E= F/q E= electric field intensity F= electrostatic force q= test charge Electric Field strength is a vector quantity. It is measured in the units (Newtons/Coulomb)

5. Electric Field problems
A 0.03 C test charge experiences a force of 20 N when placed at point A. What is the electric field intensity at point A?
E=F/q=20N/0.03C= N/C
2.What is the magnitude of the electrostatic force experienced by 8 x 10-6 C test charge when it is placed at a point where the electric field intensity is 150 N/C?
E=F/q
150 N/C=F/(8x10-6 C)
F= N

6. Visualizing Electric Fields
Electric Fields around positive and negative point charges.

7. Rules for Drawing Electric Fields
Electric field lines must begin on positive charges and end on negative charges
The number of lines beginning on a positive charge or ending on a negative charge are proportional to the magnitude of the charge.
No two field lines can cross each other

8. Rank the charges from greatest to weakest
C>B>A

9. Electric Field around Two Opposite Charges
Electric Dipole

10. Electric Field Around Two Like Charges

11. Uniform Electric Field