1. Reading Quiz 1. What is the SI unit of charge?
Coulomb
Faraday
Ampere
Ohm
Volt
2. A charge alters the space around it. What is this alteration of space called?
Charged plasma
Charge sphere
Electric ether
Electric field
Electrophoresys
Answer: A

2. 4. The electric field of a charge is defined by the force on
3. If a negative charged rod is held near a neutral metal ball, the ball is attracted to the rod. This happens
because of magnetic effects.
because the ball tries to pull the rod’s electrons over to it.
because the rod polarizes the metal.
because the rod and the ball have opposite charges.
4. The electric field of a charge is defined by the force on
an electron.
a proton.
a source charge.
a test charge.
Answer: C

3. What is the SI unit of charge?
Coulomb
Faraday
Ampere
Ohm
Volt

4. A charge alters the space around it
A charge alters the space around it. What is this alteration of space called?
Charged plasma
Charge sphere
Electric ether
Electric field
Electrophoresys

5. If a negative charged rod is held near a neutral metal ball, the ball is attracted to the rod. This happens
because of magnetic effects.
because the ball tries to pull the rod’s  electrons over to it.
because the rod polarizes the metal.
because the rod and the ball have  opposite charges.

6. The electric field of a charge is defined by the force on
an electron.
a proton.
a source charge.
a test charge.

7. The Electric Dipole

8. Coulomb’s Law - Magnitude
K = 9.0 x 109 N m2/C2
Coulomb’s contant
q1, q2 = charges
measured in Coulombs (C)
1 C is a lot of charge!
r = distance between q1 and q2
ε0 =permittivity of free space
(more relevant to future chapters)

9. Electric Force
Similar form as gravitational force (weird, huh?), except
positive and negative charges
Like charges repel; opposite charge attract

10. Net Force from Multiple Charges
An electrostatic force exists between each pair of charges according to Coulomb’s law
Add components of forces to get net force when adding multiple charges

11. The Electric Field
We begin our investigation of electric fields by postulating a field model that describes how charges interact:
Some charges, which we will call the source charges,    alter the space around them by creating an electric field.
A separate charge in the electric field experiences a force    exerted by the field.
Suppose probe charge q experiences an electric force Fon q due to other charges.
The units of the electric field are N/C. The magnitude E of the electric field is called the electric field strength.

12. The Electric Field

13. Group Problems

14. Group Problems
Workbook Volume 4
Pages 26-9 – 26-12

15. What is the net force on the 48 C charge? Field?
Group Problems
What is the net force on the 48 C charge? Field? Q1 Q4 Q3 Q2
2. Find net force
on Q1. Field? +y +x