1. A group of students performed a deconstruction and design activity to measure the charge on two conducting spheres using the apparatus below mm m A charging probe delivered the same negative charge to both spheres a) Describe and explain how the reading on the mass balance charges as the distance between spheres increases b) When r = 20mm, the balance is 0.01g Determine the magnitude of the charge on both spheres 2. An investigation was conducted to observe the motion of electrons in the electric and magnetic fields. a) Magnetic fields were produced using long straight wires carrying a current of 290 A. i) Describe the shape and strength of the magnetic eld surrounding the wire when current flows. ii) The current in the wires is too high to be measured with an ammeter Design a simple method of using a magnetic eld sensor to determine the current in the wire b) Another long wire carrying the same current is placed parallel to the original wire shown below A Electron H 2.9 x 10? ms\" (_ 290 A An electron travelling horizontally at 2.9 x 107 ms1 enters midway between the wires, where the magnetic field strength is 4.64 mT midway between the wires. i) Calculate the magnitude and state the direction of the magnetic force on the electron