Lesson 3 Electric Fields Electric field the influence

Lesson 3: Electric Fields Electric field: the influence of a charge (or charges) on the surrounding space

Formal Definitions • Electric Field: The force that would be experienced by a +1 C point charge (Newton/Coulomb). E = F / Q • Electric Field Lines: Lines that show the direction and magnitude (density of lines) of the electric field.

Electric Field Example: • Draw the electric field lines surrounding a proton and find the magnitude of the electric field 1 cm away.

Try This: Draw the electric field lines…

Try This: Draw the electric field lines…

Brain Break!

Calculations of Electric Field Strength “The force that would be “felt” by a +1 coulomb point charge. ” Example 1: a) Find the electric field midway between two charges of 2. 0 μC and 3. 0 μC located 5. 0 m apart. b) Where is the electric field ZERO?

a) Find the electric field midway between two charges of 2. 0 μC and 3. 0 μc located 5. 0 m apart. = 1440 N/C b) Where is the electric field ZERO? 2. 25 m left of the 2 μC charge

Homework • Textbook pg. 149 #1 -5 • Problem Set – Part A #1, 2, and 7

Lesson 4: More Electric Fields

Example 2: What is the magnitude and direction of an electric field that just supports an electron`s weight? Direction？ Downwards！

Practice Time! Find: a) b) c) d) e) The force on the -2 µC charge The electric field at (3, 0) The electric field at (0, 2) Where the electric field is zero The acceleration of an electron placed at (3, 0) a)

b) c) 5400 N/C, 75 O with the x axis

d) e) From (b), the electric field is -15000 N/C.

Homework • Problem Set – Part A #3 -6 (all of Part A has now been assigned)