A tiny particle with mass 5gr and charge -1mC enters in a rectangular uniform magnetic field region with a speed of 6cm/s and leaves with the same speed as shown in the figure. The region has dimensions a = 1.5cm and b = 3.0cm. Ignoring the gravitational effects, find the direction of the magnetic field, Figure says that the path of the particle inside the magnetic field region is a quar- ter circle with radius R = 1.5cm and its center is upper left corner of the region. Therefore, the magnetic force is always towards the center of its circular path. Right hand rule tells you that the direction of magnetic force ( x B) must be into the page direction for positive charge, since our particle is negatively charged then the direction of magnetic field must be flipped in out of the page. and find the magnitude of the magnetic field. Charged particles move in circular paths inside a magnetic field region, therefore; B= E (5 x 10-3 kg)(6 x 10- m/s) (10- C)(1.5 x 10- m) B = 20 T R = mv |q|B B mv |q|R V