The current flowing in a given circuit can be described by the function: I(t) = Imax(1 - e-t/τ), where Imax = 25 A and T = 2.4 s. At what time in seconds is the current equal to 75% of the maximum current? How much charge in coulombs, passes through a point in the circuit as the current increases from 0 to 75% of the maximum current?

In the figure current is set up through a truncated right circular cone of resistivity 731 №∙m, left radius a = 2.13 mm, right radius b = 2.40 mm, and length L = 2.22 cm. Assume that the current density is uniform across any cross section taken perpendicular to the length. What is the resistance of the cone? Number i L ! Units k!

this problems is giving me hard time

A copper wire has a circular cross section with a radius of 1.06 mm. (a) If the wire carries a current of 4.03 A, find the drift speed (in m/s) of electrons in the wire. (Take the density of mobile charge carriers in copper to be n = 1.10 ✕ 1029 electrons/m3.)  m/s (b) For the same wire size and current, find the drift speed (in m/s) of electrons if the wire is made of aluminum with n = 2.11 ✕ 1029 electrons/m3.   m/s