A mysterious device found in a forgotten laboratory accumulates charge at a rate specified by the expression gm = 9 - 10tC from the moment it is switched on. (a) Calculate the total charge contained in the device at t: O. (b) Calculate the totalcharge contained at t: 1 s. (c) Determine the current flowing into the device at t: 1 s, 3 s, and 10 s.

9C

-1C

I (1) = I (3) = I (10) = - 10 Amps

Explanation:

Given expression : q (t) = 9 - 10*t

a) @ t = 0, q (0) ?

q (0) = 9 - 10 * 0 = 9 C

Answer : 9C

b) @ t = 1, q (1) ?

q (1) = 9 - 10 * 1 = 1 C

Answer : 1C

c) t = 1, 3, 10 s what is I (1), I (3), I (10) ?

I = dq / dt

I = dq/dt = - 10 Amps

Hence,

I (1) = I (3) = I (10) = - 10 Amps

Answer : I (1) = I (3) = I (10) = - 10 Amps