4. (10 Points) A bent wire carries a constant current I = 1.5 A as shown on the attached figure. Note that the radius of the circular arc is 15 cm and that subtends an angle of 60. a) Find the magnetic field due to the current in the bent wire at the center of the circular arc. Please derive the form for the field, do not copy it from your cheatsheet or any other source. b) If an electron were moving to the left at the center of the arc at a speed of 7.8x 106 m, determine the magnitude and direction of the force on the electron due to the magnetic field of the bent wire