1. Electrostatics
Seo
Physics

2. Objective To mathematically observe charges in atoms
To find the Electrostatic Force between two different charges

3. Electric Charge What is an Electric Charge? 2 main charges: Units?
Atomic forms of matter
2 main charges:
Proton (+) Positive Charge
Electron (-) Negative Charge
Units?
Coulombs (C)
Numerical Value?
Proton = +1.6 x C
Electron = -1.6 x C
2 Interactions
LIKE (aka. Same) Charges = Repel
UNLIKE (aka. Different) Charges = Attract

4. Coulombs Law 𝑭 = 𝒌 |𝒒 𝟏 | | 𝒒 𝟐 | 𝒓 𝟐 What is Coulombs Law? Equation?
Magnitude or the Electric Force of two charges in an object(s) or atom(s)
Equation?
F = Force or Magnitude , q1= Charge of object 1
q2= Charge of object 2 , r = Radius, k= Coulombs constant ,
(| |) – Absolute Value- makes all numbers positive
Value of k?
9 x 109 Nm2/c2
𝑭 = 𝒌 |𝒒 𝟏 | | 𝒒 𝟐 | 𝒓 𝟐

5. Important Multipliers

6. practice
Two 0.5 kg spheres are placed 25 cm apart. Each sphere has a charge of 100 μC.
A ) Calculate the electrostatic force between them. B) Write their sign charge
Two Spheres REPEL, because both charges are (+)
𝑭 = 𝒌 |𝒒 𝟏 | | 𝒒 𝟐 | 𝒓 𝟐
𝝁𝑪=𝟏× 𝟏𝟎 −𝟔 𝑪
𝒌=𝟗× 𝟏𝟎 𝟗 𝑵 𝒎 𝟐 / 𝑪 𝟐
𝒓=𝟐𝟓 𝒄𝒎=𝟎.𝟐𝟓 𝒎
|𝒒 𝟏 |=| 𝒒 𝟐 |=𝟏𝟎𝟎 𝝁𝑪= 𝟏𝟎𝟎× 𝟏𝟎 −𝟔 𝑪=𝟏𝟎 −𝟒 𝑪
𝑭 𝒆𝒍𝒆𝒄𝒕𝒓𝒐𝒔𝒕𝒂𝒕𝒊𝒄 = 𝟗× 𝟏𝟎 𝟗 𝑵 𝒎 𝟐 / 𝑪 𝟐 × 𝟏𝟎 −𝟒 𝑪× 𝟏𝟎 −𝟒 𝑪 (𝟎.𝟐𝟓 𝒎) 𝟐 =+𝟏𝟒𝟒𝟎 𝑵

7. DIY
Two charges, Q1= +8 µC and Q2= -5 µC, are separated by a distance r= 10 cm
A) Find the Magnitude between two charges and B) Does it Repel or Attract?
Q1= +8 µC  +8×10-6 C
Q2= -5 µC  -5×10-6 C
Attracts (+) and (-)

8. Electric Field 𝑭=𝒒𝑬 What is an Electric Field? (E)
A directional field force around positive or negative charges
Units?
N / C
Equation?
E= Electric Field (N/C)
k= Coulombs Constant
(9 x 109 Nm2/c2)
q1 = Charge of object 1
r = radius or distance
𝑭=𝒒𝑬

9. Practice 𝝁𝑪=𝟏× 𝟏𝟎 −𝟔 𝑪 q1 = 5 µC  5×10-6 C 𝒌=𝟗× 𝟏𝟎 𝟗 𝑵 𝒎 𝟐 / 𝑪 𝟐
What is the magnitude and direction of the electric field meters away from a point charge, q1, with 5.0 µC
q1 = 5 µC  5×10-6 C
𝝁𝑪=𝟏× 𝟏𝟎 −𝟔 𝑪
𝒌=𝟗× 𝟏𝟎 𝟗 𝑵 𝒎 𝟐 / 𝑪 𝟐

10. DIY
What is the magnitude and direction of the electric field meters away from a point charge, q1, with +3.7 nC
q1 = +3.7 nC  +3.7×10-9 C
𝒏𝑪=𝟏× 𝟏𝟎 −𝟗 𝑪
𝒌=𝟗× 𝟏𝟎 𝟗 𝑵 𝒎 𝟐 / 𝑪 𝟐

11. Field Directions Positive charge Negative charge
Points AWAY from the charge
Negative charge
Points TOWARD from the charge

12. Electric Field ex 1

13. Electric Field Ex 2