2nd Semester AY 2011 - 2012
Physics 72 EEE: Chapter 27-28 Problem Set Part I Name: Lecturer: Carlos Baldo III, M.Sc.
Date: Section: TWHFA
Score:
/ 10
Solve each problem clearly and completely for full credit. For multiple-choice problems, encircle the letter of your answer. 1.
Fluxes. Which of the following surfaces will have the largest magnetic flux?
For the next two numbers, consider four point charges (with equal magnitude Q) moving with equal speeds, v1, as shown by the arrows. All four charges are initially at a distance s from point P. 2.
Apat-dapat. What is the net magnetic field at point P for that particular instant of time? Magnitude: (in terms of o,, s, Q and v1, if applicable) Direction: (use arrow, if applicable)
3.
E-Pal. If at the instant the four charges are placed in space in such positions, an electron is placed at point P that initially moves to the left with speed, v2. What will be the magnetic force acting on the electron? Magnitude: (in terms of o,, s, Q, e and v1, if applicable) Direction: (use arrow, if applicable)
4.
B4 colission 1. Two positive point charges are moving towards each other with equal speeds v at an instant of time. Before the collision of the two point charges, what is the magnitude of the net magnetic field at point P with distance R and angle of 30o from each charge? (Neglect relativistic effects.) Magnitude: (in terms of o,, R, q and v, if applicable)
5.
Sandwich. The diagram shows a cross-section of a straight wire carrying a flow of electrons out of the page. The wire (whose cross-section is shown as a circle) is between the pole faces of permanent magnets. What is the direction of the magnetic force exerted on the wire? Direction: (use arrow)
2nd Semester AY 2011 - 2012
Physics 72 EEE: Chapter 27-28 Problem Set Part I
For the next three numbers, consider the figure at the right. Two very long wires carrying current are equidistant from point Me. 6. Top Wire. What is the magnetic field produced by the top wire
on the bottom wire? Magnitude: (in terms of o,, s and I, if applicable) Direction: (use arrow, if applicable) 7. Net Field. What is the net magnetic field produced by the two
wires at point Me? Magnitude: (in terms of o,, s and I, if applicable) Direction: (use arrow, if applicable) 8. Physics Got Current. A third wire, with length L and carrying current I directed into the page, is
placed at point Me. Determine the net force acting on the third wire? Magnitude: (in terms of o,, s and I, if applicable) Direction: (use arrow, if applicable) 9. Loop. Two independent current-carrying circular loops are
lying on the plane of this paper. Loop 1 has radius r and counter-clockwise current I. Loop 2 has radius 2r and clockwise current 2I. Determine the ratio of the (vector) magnetic fields at the axes of these loops, B1 and B2? B1/B2 = ______
10. Break na tayo! A proton and an electron move in opposite directions
from the same point in space with equal speeds. If you want to measure the lowest magnitude of magnetic field produced by the two charges, where will you place the detector? All points (A to E) are equidistant from the origin.
11. Biot-Savart Law. Four wires carrying equal currents I with
each having equidistant centers of wire segments dlA, dlB, dlC and dlD to point P but different thicknesses as shown in the figure. Which of the following wire segments will yield the highest magnitude of magnetic field at point P? E. All wires produce the same magnetic field magnitude
