Conductors + Insulators + Electric Fields
If an electron is placed within an electric field pointing south, what direction will the electron move?
North (negative moves opposite of the E field)
(Diagram on slides)
Charged particles of –2.0nC and +8.0nC are located at x = –2.0cm and x = +2.0cm, respectively. At what point on the x-axis is the electric field equal to zero?
x = -6.0cm
(Prelec 21B, slide 7)
Fill in the blank: Electric Potential only depends on your ___ in the electric field.
Position
(Prelec 22A)
On a sheet of paper, draw:
Three capacitors (C1, C2, and C3) in series attached to a battery. If the capacitance of each is 2uF, 5uF, and 6uF respectively, what is the equivalent capacitance of C1, C2, and C3?
C = 1.15 uF
True/False: Electric field lines cannot ever cross each other.
Complete the following sentences:
Electric fields can only (start/terminate) on positive charges.
Electric field can only (start/terminate) on negative charges.
Electric field lines cannot ever cross each other: True
Electric fields can only start on positive charges.
Electric field can only terminate on negative charges.
(Prelec 21B, Slide 4)
Consider an x-y coordinate graph where a charge of +8.0nC (Q1) is placed at the coordinates (-4.0m, 0m). A second charge of -16.0nC (Q2) is placed at (0m, -6.0m). What is the magnitude of the total electric field at the origin due to these two charges?
6.0 N/C
(Winter 2023 Phys2B Exam)
If I placed a positive test charge (+q) between two oppositely charged plates, and then released from rest, which plate would it move towards? Would it be going towards higher voltage, or towards lower voltage?
Positive to negative plate.
Going from high voltage to low voltage.
(Prelec 22B)
True/False:
1) Capacitors in parallel all have the same charge.
2) Capacitors in series all have the same charge as their (the in series capacitors) equivalent capacitor.
1) False
2) True
(Prelec 23B, Slide 16)
Two uncharged metal spheres (Sphere L and Sphere M) are in contact with each other. A negatively charged rod is brought close to L, but not touching it. The two spheres are then slightly separated (no longer touching). The rod is then withdrawn from this system. As a result of this process, are spheres L and M each positive, negative, or neutral?
Sphere L is positive, Sphere M is negative
(Winter 2023 Phys2B Exam)
An electron in the picture tube of an older TV set is accelerated from rest by a uniform electric field of 20,000N/C over a distance of 25.0cm. What is the acceleration and speed of the electron as a result of this acceleration (assume it started from rest)?
a = 3.51x10^15 m/s^2
v = 4.19x10^7 m/s
(Prelec 21D, Slide 18)
An electron in the picture tube of an older TV set is accelerated from rest through a potential difference ΔV = 5000V by a uniform electric field. What is the change in potential energy of the electron? What is the speed of the electron as a result of this acceleration (assume it started from rest)?
ΔU = -8.0 × 10^(-16) Joules
v= 4.2 × 10^7 m/s
(Prelec 22A, slide 16)
(Diagram on SI Slides)
Consider the circuit diagram to the right consisting, which is composed of a battery and three capacitors. You can assume that they have all reached static equilibrium.
A) What is the equivalent capacitance for this circuit (in μF)?
B) What is the energy stored on the 4.0 μF capacitor (in μJ)?
A) 1.87 μF
B) 62.7 μJ
(Prelec23C, Slide 15)