An RC circuit is powered by a constant voltage source. An oscilloscope is connected across the capacitor and adjusted to give the stable display. The timebase control is set to 20 milliseconds per division. Use the scope trace to determine the value of the circuit's time constant.

Along wire carrying a 4.2 a current perpendicular to the xy-plane intersects the x-axis at x=−1.7cm. a second, parallel wire carrying a 3.0 a current intersects the x-axis at x=+1.7cm. part a at what point on the x-axis is the magnetic field zero if the two currents are in the same direction? express your answer to two significant figures and include the appropriate units.