PHYSICS 3204 PUBLIC EXAM QUESTIONS (Magnetism &Electromagnetism) NAME: August 2009--------------------------------------------------------------------------------------------------------------------------------- 32. What is the polarity of X and Y for the magnets shown below? X Y (A) north north (B) north south (C) south north (D) south south 33. Which represents the magnetic field produced around the straight current-carrying conductor below? (A) (B) (C) (D) 4 34. What is the force on a 2.1 m long wire, carrying 0.56 A of current, placed perpendicularly in a 4.6 10 T magnetic field? 4 4 3 3 (A) 1.2 10 N (B) 5.4 10 N (C) 2.0 10 N (D) 8.2 10 N 35. What are the charges on the three charged particles fired into the magnetic field as shown below? P Q R (A) negative negative positive (B) negative neutral positive (C) positive neutral negative (D) positive positive negative 36. A current-carrying conductor is placed perpendicular to a magnetic field and experiences a force of 0 magnitude, F1. What will be the new force if the wire is placed at an angle of 30.0 to the magnetic field? (A) 0.500 F1 (B) 0.866 F1 (C) 1.00 F1 (D) 2.00 F1 3 37. At what distance from a wire carrying 3.5 A of current will the magnetic field strength be 9.2 10 T? 7 6 5 4 (A) 7.6 10 m (B) 1.5 10 m (C) 7.6 10 m (D) 1.5 10 m
38. What is the direction of current flow and compass deflection as the magnet is pulled left in the diagram shown? Current Direction Deflection of Compass (A) P to Q left (B) P to Q right (C) Q to P left (D) Q to P right 39. What is the type of generator and the frequency of rotation for the output shown below? Type Frequency (Hz) (A) AC 5 (B) AC 10 (C) DC 5 (D) DC 10 40. A conductor is initially at rest in a magnetic field as shown. In which direction should the conductor be moved so that current is induced as shown? (A) into the page (C) towards bottom of the page (B) out of the page (D) towards top of the page 2% 52.(d) A 75 resistor that is 0.28 m long is placed in a uniform magnetic field of 0.25 T. If the resistor 2 experiences a force of 4.0 10 N when it is perpendicular to the magnetic field, calculate the voltage across the resistor. 3% 52.(e) Calculate I 1 so that the net magnetic field at point P is zero.
2 3% 52.(f) An electron is projected perpendicularly into a 3.00 10 T magnetic field and travels in a circle with 3 radius 7.5 10 m. Calculate the minimum velocity required to maintain the circular path. June 2009------------------------------------------------------------------------------------------------------------------------------------ 33. Which describes the magnetic field lines around the current carrying conductor shown below? (A) clockwise concentric circles (C) parallel lines pointing down (B) counterclockwise concentric circles (D) parallel lines pointing up 34. A solenoid is surrounded by four compasses as shown. Which compass reading is correct? (A) A (C) C (B) B (D) D 35. What is the magnetic field strength at point P, 0.020 m away from a wire carrying a 1.5 A current? 9 (A) 2.7 10 T 9 (B) 6.0 10 T 5 (C) 3.0 10 T 5 (D) 1.5 10 T 7 36. An electron is projected perpendicularly into a magnetic field with a velocity of 3.3 10 m/s and 13 experiences a force of 1.3 10 N. What is the magnitude of the magnetic field? 25 2 1 13 (A) 6.9 10 T (B) 2.5 10 T (C) 4.1 10 T (D) 2.7 10 T 4 0 37. A 0.040 m long wire is placed in a 1.2 10 T magnetic field at an angle of 29 to the field and 6 experiences a force of 9.2 10 N. What is the current in the wire? (A) 0.25 A (B) 1.9 A (C) 2.2 A (D) 4.0 A Page 3
38. A proton moves parallel to a long straight current-carrying conductor as shown. In which direction will the proton be deflected? (A) into the page (B) out of the page (C) towards bottom of page (D) towards top of page 39. What is the direction of the induced current in the wire below if it is pulled upwards? (A) into the page (B) left (C) out of the page (D) right 40. Two hollow-core solenoids, X and Y, are connected by a wire, as shown in the diagram provided. Two bar magnets, 1 and 2, are suspended just above the solenoids. What will happen to magnet 2 if the south pole of magnet 1 is dropped through solenoid X? (A) attracted by a magnetic force toward solenoid Y (B) attracted by an electric force toward solenoid Y (C) repelled by a magnetic force away from solenoid Y (D) repelled by an electric force away from solenoid Y 3% 52.(d) A 0.025 m long wire segment, XY, is positioned perpendicular to a 0.750 T magnetic field as shown. When a current is passed through this wire segment, it experiences a 0.20 N force upwards. Calculate the magnitude and give the direction of the current through the wire. Page 4
3% 52.(e) The diagrams provided show a metal rod, of mass m, suspended in a constant magnetic field by two identical wires. In diagram 1, there is no current in the wires, but in diagram 2, a current flows as shown. Compare the tension in the wires for diagram 2 to that for diagram 1. Explain your answer. 3% 52.(f) Calculate the magnitude and direction of the magnetic field strength at point P in the diagram provided. August 2008-------------------------------------------------------------------------------------------------------------------- 36. Which occurs when protons and electrons enter a magnetic field that is parallel to their direction of motion? (A) Both protons and electrons are deflected. (C) Only electrons are deflected. (B) Neither protons nor electrons are deflected. (D) Only protons are deflected. Page 5
37. Which shows the final position of a bar magnet that is free to rotate in a magnetic field and is initially positioned as shown below? (A) (B) (C) (D) 38. A 2.0 m long current-carrying conductor is placed perpendicular to an external magnetic field. The graph below shows how the force on the conductor changes as the current is varied. What is the magnitude of the external magnetic field? (A) 0.12 T (C) 0.46 T (B) 0.23 T (D) 8.7 T Page 6