Aclosely wound, circular coil with radius 2.30 cm has 740 turns. a. what must the current in the coil be if the magnetic field at the center of the coil is 0.0790 t ? express your answer to three significant figures and include the appropriate units. ii = 3.91 a submitprevious b. at what distance x from the center of the coil, on the axis of the coil, is the magnetic field half its value at the center? express your answer to three significant figures and include the appropriate units.

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".