Please help me answer the following problems:

Problem 4 (25 points) The figure below shows a mass spectrometer, a device used to measure the masses of ions. Consider a positive ion of unknown mass m and charge q = 4.8 x 10-19 C. The ion is first accelerated from rest through a potential difference of magnitude |V| = 250 V inside a source. After leaving the source, it travels upward at constant speed and enters a region of uniform magnetic field B = 0.25 T directed out of the page. The ion then moves in a semicircle of radius R within the field, striking a plate at a horizontal distance x = 9.0 m from its point of entry. Ignore the effect of gravity. 2 AV F= PM . 1. 02 2 82 RQB 2 my = k mm = ZK (a) Show clearly that the kinetic energy of the ion as it leaves the source is 1.2 x 10-16 J. (6 points) $ (b) Determine the mass m of the ion. (13 points) (c) Suppose it is desired that the ion travel through the magnetic-field region without being deflected (i.e., at constant speed along a straight line). In addition to the magnetic field, there would need to be an electric field in this region. What is the required direction of the electric field? Justify your answer clearly. (6 points) DV = DU DU = DVqo 40Problem 5 (25 points) A 25-cm long massless bar with resistance 0.075 Q is pulled upward on zero-resistance rails at a constant speed of 15 cm/s, as shown below. The circuit is surrounded by a uniform magnetic field of magnitude 1.8 T directed out of the page. Ignore the effect of gravity. E = BLL (a) Using Faraday's Law, calculate the magnitude of the induced current in the circuit. (Note: You must show your work; simply plugging numbers into a result derived in class is not enough!) (12 points) (b) Using Lenz's Law and stating your reasoning, determine the general direction of the induced current in the circuit. Then, using the right-hand rule, determine the specific direction of the magnetic force on the bar. (9 points) (c) Find the magnitude of the applied force required to pull the bar upward at constant speed. (4 points) 6 - B X - ) = BL . X