Wires 1 to 5 meet at a junction. Wires 1 to 3 carry currents 2 A, 6 A and 5 A into the junction. Wire 4 carries a current 4 A out of the junction. What is the current in wire 5?

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?