Download Physics Lecture #22

Mon. Jan. 26 – Physics Lecture #22
The Electric Field
1. Forces & Fields
2. Superposition
3. Electric Field due to Continuous Charge Distributions
Example: An electron placed in a gravity field experience a gravity force of
6.1 x 10–10 N.
a) What is the magnitude of the gravity field?
b) A proton is placed in that same gravity field. What is the magnitude of the
gravity force on that proton?
Example: An electron placed in an electric field experience an electric force of
6.1 x 10–10 N.
a) What is the magnitude of the electric field?
b) A proton is placed in that same electric field. What is the magnitude of the
electric force on that proton?
ConceptCheck: An electron moving to the right enters a region with electric field
as shown. Which way does the electron deflect as it passes through the electric
field?
1. Up
2. Down
3. Right
4. Left
5. Into or out of page
6. No deflection
?
E
PhET Interactive Simulations – Charges and Fields
http://phet.colorado.edu/en/simulation/charges-and-fields
Example: The sketch shows two point
charges located in the x-y plane:
q1 at the origin and q2 at (0 m, 4 m).
Also consider a field point at (3 m, 0 m)
a) Determine the unit vector from q1
to the field point.
b) Determine the unit vector from q2
to the field point.
c) Determine the electric field
at the field point due to q1 and q2.
d) How does your answer change if q2 is negative?
e) A charge q3 is placed at (3 m, 0 m). What is the electric force acting on q3?