Electrostatics
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Transcript of Electrostatics
Part 3
The electric field can push AND pull charges Because there are two types of charges (+
and -)
The gravitational field can only pull Only positive masses
Charges cause an electrical field.Each charge creates its own electric
field in the surrounding space.
Electric Field is a vector quantity Has magnitude and direction
Use Electric Field lines(lines of force) to show the Electric Field
Electric field direction from charge that creates the field: Away from positive charge
Toward negative charges
The lines begin on positive charges and end on negative charges.
Draw lines perpendicular to charge Lines never cross
Electric field strength: The closer to the charge, the stronger the field The closer the field lines, the stronger the field The farther away, the weaker the field
Electric field strength: The number of lines are proportional to
strength The more lines the stronger the field
Electric field strength: (quantitative)
E = kq/d2
▪ Depends on Charge and distance
E = Electric field strength (Newton/Coulomb, N/C)
k = 9.0 x 109 Nm2/C q= charge causing the field (Coulomb, C) d or r = distance (meters, m)
A fly accumulates 3.0 x 10-10 C of positive charge as it flies through the air. What is the magnitude and direction of the electric field at a location 2.0 cm away from the fly?
q = 3.0 x 10-10Cd or r = 2.0 cm = _____ mE = ? equation E = kq/ r2
E = (9.0 x 109)(3.0x10-10) (0.020)2
E = 6750 N/C
0.020
Electric Field = force exerted on positive charge
If +q = force in same direction (pull) of the field If -q = force in opposite direction (push) of the field
The strength of the electric field…
E = F/qE = strength of the field
(Newton/Coulomb, N/C)F = Force exerted on charge in field
(Newton, N)q = charge (Coulomb, C) that sits in
the field; experiences the force
A charge of -2.0 xC is placed in a uniform electric field of strength 5000 N/C that points downward. What is the magnitude and direction of the force experienced by this charge?
E = F / q 5000 N/C= F / (-2.0 x 10-6C) (-2x10-6 )(5000)=F -0.01N=F magnitude of the forcedirection? - 2 charge, the force on the electron is opposite the field!
A charge of -2.0 xC is placed in a uniform electric field of strength 5000 N/C that points downward. What is the magnitude and direction of the force experienced by this charge?