Magnetic Field and RMS Voltages Questions

I need help with a Physics question. All explanations and answers will be used to help me learn. Question: 3Consider a point P at a distance R = 10.5 cm on the perpendicular bisector of a straight wire of length 35.0 cm carrying a current of 75.0 mA. Calculate the magnitude of the magnetic field at P due to the current. Hint: use the Biot-Savart law realizing that the length is not very long.Question: 4An AC source with a maximum voltage of 120 V and f = 40.0 Hz is connected between points a and b in the figure below. Calculate the rms voltages between the following points.a) a and bb) b and cc) c and dd) b and d