Question

1. True or false? The best insulating materials are made almost entirely of neutrons.

2. An initially uncharged capacitor C is connected in series with a resistor R and a batter V_b. At the instant that the switch is closed (t=0), the capacitor begins to charge.

(a) Draw a simple graph (NO labeled axes or numbers needed) that represents how the potential difference across the capacitor varies with time as the capacitor charges.

(b) Draw a simple graph (NO labeled axes or numbers needed) that represents how the potential difference across the resistor varies with time as the capacitor charges.

(c) Suppose that the capacitor is considered "fully charged" when it has reached 99.90% of its eventual maximum charge. If C = 650. μF and R = 480. Ω, what is the amount of time needed for the capacitor to reach this threshold?

A. 1.4 s

B. 2.2 s

C. 3.9 s

D. 5.2 s

E. 8.8 s

(d) Which one or more the following would shorten the time needed for the capacitor to reach its 99.90% threshold in the previous question?

I. reducing the value of Vb

II. reducing the value of R

III. reducing the value of C

A. II only

B. III only

C. I or II only

D. II or III only

E. I, II, or III

Answer 1