A capacitor consists of two closely spaced metal conductors of large area, separated by a thin insulating foil. It has an electrical capacity of 3800.0 μF and is charged to a potential difference of 78.0 V. Calculate the amount of energy stored in the capacitor. Tries 0/20 Calculate the charge on this capacitor when the electrical energy stored in the capacitor is 6.84 J. Tries 0/20 If the two plates of the capacitor have their separation increased by a factor of 4 while the charge on the plates remains constant, by what factor is the energy stored in the capacitor increased?

- E = 11.55J

- Q = 0.17C

- E' = (1/4)E

Explanation:

- To calculate the amount of energy stored in the capacitor, you use the following formula:

C: capacitance = 3800.0*10^-6F

V: potential difference = 78.0V

The energy stored in the capacitor is 11.55J

- If the electrical energy stored in the capacitor is 6.84J, the charge on the capacitor is:

The charge on the capacitor is 0.17C

- If you take the capacitor as a parallel plate capacitor, you have that the energy stored on the capacitor is:

A: area of the plates

d: distance between plates

If the distance between plates is increased by a factor of 4, you have:

Then, the stored energy in the capacitor is decreased by a a factor of (1/4)

John Singleton Copley's portrait shows Paul Revere, an artisan. He is a famous silversmith and etcher. In this portrait, it seems the artisan is about to begin engraving the silver teapot he is holding on his hand, but we have interrupted him by looking at him on the portrait. He regardfully stares at us. He is not only an artisan, but a full artist. He is a smart man looking at us attentively. He is trying to guess what is the reason why we are disrupting him as he is a very important citizen in his society. Everybody knows that he is an excellent artisan, his work is widely known and recognized in the society he lives in.

This portrait was done in 1768. The painting technique used is oil on canvas. Its dimensions are 35 inches high and 28.5 inches wide. At present, it is at Carolyn A. and Peter S. Lynch Gallery (Revolutionary Boston, gallery 132.)

John Singleton Copley emigrated to London when Paul Revere made his legendary midnight ride to alert the Good citizens that the British were coming. He painted this portrait of Paul Revere some years earlier, when Revere was known as a silversmith with a flourishing Boston trade, but not as an American hero yet. Although Revere was active by then, even in revolutionary politics, Copley prudently kept the portrait free from any hint of controversy. We can see that the portrait captures the qualities that allowed Revere to play an instrumental role in colony times: physical strength, moral certainty, intelligence, and explicit dedication to a cause.