Conceptual
Word Problems
More Word Problems
Extra Practice
100
What is happening to the proton's electric potential energy?
Kinetic Energy decreases so potential energy increases
100
Two small plastic spheres each have a mass of 3.5 g and a charge of -72 nC. They are placed 3.2 cm apart (center to center). What is the magnitude of the electric force on each sphere?
4.56x10^-2 N
Coulomb's Law
100
A 21 nC charged particle experiences an electric force of 0.083 N. What is the magnitude of the electric field at the particle's position?
E= 3.95x10^6 N/C
F=qE
100
What is the current through the 3 Ω resistor?
I=1 A
V=IR
(9V-6V)=I(3ohms)
3V=I(3 ohms)
3 V/3 Ohms=I
200
What is the direction of the electric field at the dot in the figure shown below?
Down
200
A battery and a resistor form a circuit. The resistor dissipates 0.80 W. Now, two batteries, each identical to the original one, are connected in series with the resistor. What power does it dissipate?
P1=(V)^2/R =0.80 W
P2=(2V^2)/R=4V^2/R=3.2 W
200
Describe the electric field strength and the electric potential at this point midway between the equal but opposite charges.
E points to the right
V=0
Midpoint means = distance
V1+V2=0
V2=K(-q)/d
V1=K(+q)/d
200
Which resistor dissipates more power?
The 1 ohm resistor
P=∆V^2/R
Same ∆V
P and R inversely proportional
300
How do electric potentials differ in size in a parallel-plate capacitor?
negative - smallest
Positive - largest
300
What is the electric potential at the point labeled P in the figure?
V=435 V
v=K[(q1)/(r1)+(q2)/(r2)+(q3)/(r3)]
300
A wire carries an 8 A current. What is the current in a second wire that delivers twice as much charge in half of the time?
32A
I1=q/t
I2=(2q)/(t/2)=4q/t
300
What happens to the current of the battery when the switch closes?
I increases
Req decreases
∆V Doesn't Change
400
Compare and contrast electric potential energy. What equation shows the relationship between the two?
Elec. Pot. = V - Source Charge
V=Kq/r
Elec. Pot. Energy = U - 2 point charges
Uelec=
K(q1*q2)/r
Uelec=
qV
400
A 20 Ω resistor is connected to the terminals of a 2.5V battery. What is the current of the circuit? What is the power of the circuit?
P=0.3125 W (J/s)
V=IR
P=I^2*R
400
An electron moves between two plates and experiences an increase in kinetic energy of 4.5x10^-18 J. Calculate ΔV=Va -Vb of the plates.
∆V=28.125 Volts
W=q∆V
500
Going around in the direction of current flow, what is happening to the electric potential across the battery and across the resistor, and why? Assume it is a simple circuit.
Electric potential increases across the battery and decreases across the resistor.
Kirchoff's Loop Rule
∆V(R)=-IR
∆Vbat=+emf
500
The current flowing through the circuit contained within a flashlight is 0.5 A and the voltage applied to the circuit is provided by 2 AA batteries, which is 5.0 V. Calculate the power delivered to the bulb and the electrical energy consumed in 5 minutes of operation of the flashlight.
P=750 J
P=IV(emf)
∆E=P∆t
500
Find the magnitude of the potential difference across each resistor.
R=17.5 ohms
10V-5V-(0.08A*80ohms)-(0.08A*R)=0
5V-0.08A(80ohms-R)=0
5V=0.08A(80ohms-R)
62.5ohms=80ohms-R
-17.5ohms=-R