(1) A positive charged particles is undergoing uniform circular motion of radius, r in a uniform magnetic field, B. By what factor would the magnetic field need to change for the radius to be 2r? (a) 2 (b) 1/2 (c) 2 (d) 1/2 (2) Select all that must be true for a charged particle to experience a magnetic force: (a) it must be moving with a component of velocity which is perpendicular to the magnetic field (b) it must be a positive charge (C) it must be moving in any direction (d) it must be within a magnetic field