Question 2 (10 marks) Consider a capacitor made with square plates that are 1 cm on a side, and separated by 0.01 mm, with paper (dielectric constant=3.6) between the plates. a) What is the capacitance of the capacitor? (2 marks) b) What magnitude of charge is on one of the plates if the capacitor is charged to a potential of 9 V? (1 marks) c) c) What is the magnitude of the electric field between the plates when the capacitor is charged to a potential of 9 V? (1 marks) d) An electron is launched from the positive plate travelling towards the negative plate with a speed of 2,000,000 m/s. How fast is the electron moving as it comes out the other side? (6 marks) Question 3 (10 marks) Consider two parallel conducting wires separated by a distance d. The wires are carrying currents /1 and 12 which flow in the same direction. In order to balance the forces on the wires, a third wire is placed in the system. Where will the third wire need to be positioned, and how strong must its current be? Note: the currents /1 and 12 are not necessarily equal. b) What force is required to keep the bar moving at a steady pace? (1 mark) c) If the rod becomes stuck, how quickly does the magentic field need to change (in T/s) to maintain the same current? Should the field strength increase or decrease? (3 marks) Question 4 (7 marks) Suppose a current loop consists of a fixed "U" shape and a moveable conducting bar connecting the ends of the "U" as below: The radius of the rounded part is 3 cm. The U is made of wire and has negligible resistance while the resistance of the bar is 6 Ohms. a) If the entire U shape is in a region with uniform magnetic field of 4 T out of the page, what is the current (magnitude and direction) that flows if the rod is dragged to the right at 5 m/s? (3 marks) b) What force is required to keep the bar moving at a steady pace? (1 mark) c) If the rod becomes stuck, how quickly does the magnetic field need to change (in T/s) to maintain the same current? Should the field strength increase or decrease? (3 marks) - Question 5 (3 marks) What is the effective capacitance of the following circuit, if C, = 3F, Cz = 8F, and C3 = 5F