Electrostatics Seo Physics

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

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 10-19 C Electron = -1.6 x 10-19 C 2 Interactions LIKE (aka. Same) Charges = Repel UNLIKE (aka. Different) Charges = Attract

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

Important Multipliers

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

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 (-)

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

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 0.25 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

DIY What is the magnitude and direction of the electric field 0.75 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

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

Electric Field ex 1

Electric Field Ex 2