A capacitor, capacitance C, is charged via a voltage source, then disconnected f

Question

A capacitor, capacitance C, is charged via a voltage source, then disconnected from the sources and connected to a resistor R. How much charge remains on the capacitor as the time t = 2RC? Using Gauss's law, explain why the charges inside a conductor have to be on the surface. For a positively charged particle moving in the +x direction, explain how we can deflect the particle upwards (+y direction) using 1-a magnetic and 2- electric field Using what we learned in class. Explain how you can generate electric power from a hydraulic damn or a wind turbine Draw the electric field lines for this system:

Explanation / Answer

a) As during discharging, Q=Qo exp(-2RC/RC)=13.5 %

b) We can prove this using Gauss’s law. Choose a gaussian surface that everywhere lies just inside the conductor surface. We just learned that the electric field must be zero everywhere on this gaussian surface so that the flux of E over this surface is zero; so by Gauss’s law, there can be no internal net charge. All the net charge must therefore lie on the surface of the conductor. This statement does not tell us how the charge is distributed on the surface, but if the surface is symmetric, such as a sphere, then the net charge will distribute itself uniformly.

c) The magnetic field in -z-direction (from Lorentz law) and electric field in +y-direction(from Coulomb’s law) will deflect the particle in +y-direction.

d) The conducting coil rotates due to air or water and current in a strong magnetic field.The rotation causes the change in the flux that induces a current in the coil.

e)  One common convention is to surround more charged objects by more lines. Objects with greater charge create stronger electric fields. By surrounding a highly charged object with more lines, one can communicate the strength of an electric field in the space surrounding a charged object by the line density. So, there will be more number of electric field lines for +2Q charge than that on the +Q charge.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.