Identical Capacitors - Physics - Solved Paper, Exams of Physics

Download Identical Capacitors - Physics - Solved Paper and more Exams Physics in PDF only on Docsity! Answer 1 (a) The diagram should look something like this, i.e., an equal number of -}ve and -ve charges on the metal surfaces on either side of the paper. Metal and the student should make it very clear in writing that the charges are on the surface of the metal plates {b) The arrangement is equivalent to two identical capacitors in parallel {5 marks]. The total capacitance is therefore twice the capacitance of a single capacitor: A C= Deon _ 2x 8,85 x 107” x 4.2 x (15.0 x 1077)? — 0.45 x 10-3 = 3.720F Answer 2 {a} By symmetry, and the right hand rule, the magnetic field must be as shown in the diagram (ce below. Use an Amperian loop as shown The contribution to the integral of B.ds from the vertical segments is zero. The contribution from the horizontal segments is 2BI. This equals the enclosed current, which is J//a. Using Ampere’s Law: 2B = Holl a or 1 B= Fqlol Above the plane, the magnetic field is in the —y direction, so Loo. Ba ~gyHold where B and j are vectors. The only change from part (a) is that the magnetic field is now in the +y direction: 1 Bay m0ll where B and j are vectors. This is essentially the same problem as for part. (a). The total current flowing through the Amperian loop is now oly[3 marks:. So, 2Bl= poole, therefore B= 5ueoed where DB and 7 are vectors.