Units!
Electric Potential
Volt
What is the Law of Reflection?
The angle of reflection is equal to the angle of incidence.
Do electric field lines ever cross?
No
Is electric potential = to potential energy?
No
In what direction does a conventional current flow?
Positive to negative
Electric Power
Watts
Define a focal point.
The point where all parallel light beams would intersect after reflection.
What force exists between 2 charges at rest?
Electrostatic Force
What is a capacitor?
A device that stores a charge.
What is the cute mnemonic that the book gives us to remember the equation for Ohm's Law?
Twinkle, twinkle, little star.
Voltage equals I times R.
Capacitance
Farad
With a concave mirror, what is the relation between the focal point and radius of the curvature of the mirror?
f = R/2, Focal point is the 1/2 the radius.
What Law says that the net amount of electric charge in the universe is constant?
The Law of Charge Conservation
Positive, because EP depends only on the stationary charge.
Out of which pole do magnetic field lines come out of?
Out of north into south.
Electric Current
Ampere
Draw a ray tracing diagram to illustrate what an image will look like if it is 2.0 cm away from a concave, spherical mirror whose radius of curvature is 5.0 cm.
Image is virtual, up-right, and enlarged.
What do we call a substance through which a charge cannot flow?
An insulator
An old fashioned tv screen was made with a CRT. What does CRT stand for?
Cathode Ray Tube
What do we call a substance that can become magnetic under the influence of an external magnetic field?
Paramagnetic
Resistance
Ohm
What is the angle of refraction if light traveling in air is incident on glass at an angle of 51o? The index of refraction for the glass is 1.42. (Hint: Snell's Law: n1sin(θ1)=n2sin(θ2) )
(1.00) sin (51o) = 1.42 sin (θ2)
.777 = (1.42) sin (θ2)
0.55 = sin (θ2)
sin-1 (0.55) = θ2
33.2o = θ
Two charges (3.4 C and -1.2 C) exert an instantaneous electrostatic force of 1.1 x 1010 N towards each other. At that instant, how far apart are the two charges? (Hint: Use Coulomb's Law)
1.1 x 1010N = [(9.0 x 109 Nm2/C2)(3.4C)(1.2C)] / r2
1.1 x 1010N = (3.67 x 1010 Nm2) / r2
r2 = (3.67 x 1010 Nm2) / 1.1 x 1010N
r2 = 3.34 m2
r = 1.83 m
What is the capacitance of a capacitor that stores 9.09 x 108C of charge at 9.00V?
V = Q/Cq
9.00V = 9.09 x 108C / Cq
Cq = 9.09 x 108C / 9.00V
Cq = 1.01 x 108F
What is the power drawn by the following circuit? (Extra practice problem #8 for Module 15 -- Page 581)
Find the current = 1.2 Amps
Solve for power = 1.8 Watts