Determine the focal length of a concave mirror if: (a) with the distance between an object and its image being equal to 1-15 cm, the transverse magnification ? 2.0; (b) in a certain position of the object the transverse magnification is ? ? 0.50 and in another position displaced with respect to the 1s former by a distance l- 5.0 cm the transverse magnification p, - =-0.25

Point charges q1=+2.00μc and q2=−2.00μc are placed at adjacent corners of a square for which the length of each side is 1.50 cm . point a is at the center of the square, and point b is at the empty corner closest to q2. take the electric potential to be zero at a distance far from both charges. part a what is the electric potential at point a due to q1 and q2? express your answer with the appropriate units.