Number 17 Physics

The current in a wire varies with time according to the relationship I = 55 A - (0.65 A/s^2) t^2. How many coulombs of charge pass a cross section of the wire in the time interval between t=0 and t=8.0 s?

(2 Points)

◯ 120 C

◯ 250 C

◯ 330 C

◯ 420 C

◯ None of the Above

 

The plates of a parallel-plate capacitor are 2.50 mm apart, and each carries a charge of magnitude 80.0 nC. The plates are in vacuum. The electric field between the plates has a magnitude of 4.00 x 10^6 V/m. What is the capacitance? *

(2 Points)

◯ 8.00 pF

◯ 8.00 nF

◯ 12.0 pF

◯ 12.0 nF

◯ None of the Above

Electric eels and electric fish generate large potential differences that are used to stun enemies and prey. These potentials are produced by cells that each can generate 0.10 V. We can plausibly model such cells as charged capacitors. How should these cells be connected to produce a total potential of more than 0.10 V.

(2 Points)

◯ Parallel

◯ Series

◯ Wye

◯ Delta

◯ None of the Above

A 5.80-uF (microFarad), parallel-plate, air capacitor has a plate separation of 5.00 mm and is charged to a potential difference of 400 V. Calculate the energy density in the region between the plates, in units of  J/m^3.

(2 Points)

◯ 0.0153 J/m^3

◯ 0.0283 J/m^3

◯ 0.0382 J/m^3

◯ 0.0415 J/m^3

◯ None of the Above