1. Four identical conducting loops move through a region with a magnetic field. At the instant shown, all loops are moving at the same speed, with direction indicated by arrows. There is a uniform magnetic field pointing into the page in Region I, but there is NO magnetic field in region II (at the top). All loops are identical, but loop 3 is oriented differently than the others, the wider side is horizontal. Ignore any interaction between the loops, neglect gravity and air resistance. Region II (no field 3 2 up here) X Region I (uniform B,8 8 8 8 shown) 8 8 cwy i) At the moment shown in the picture above, circle below for each of the loops whether the current flows clockwise (CW), counterclockwise (CCW), or there is no current flowing at all. ii) Also circle what direction the resulting net magnetic force on that loop would point. 2 points for each correct answer. Total of 8 points possible. Loop 1: current direction: CW CCW No current magnetic force on loop: up, down, left, right, into page, out of page, no force. Loop 2: current direction: CW CCW No current magnetic force on loop: up, down, left, right, into page, out of page, no force. Loop 3: current direction: CW CCW No current magnetic force on loop: up, down, left, right, into page, out of page, no force. Loop 4: current direction: CW CCW No current magnetic force on loop: up, down, left, right, into page, out of page, no force.2. Consider the circuit below. The light bulbs are identical and initially the capacitor is uncharged. switch (a) (2 points) The switch is closed at time =0. Describe the behavior of bulb A from just after the switch is closed to a long time later. Explain your reasoning. (b) (2 points) Describe the behavior of bulb B from just after the switch is closed to a long time later. Explain your reasoning. (c) (2 points) Compare the brightness of bulbs A and B from just after the switch is closed to a long time later. Explain your reasoning. 3. Draw a schematic diagram that best represents the realistic circuit shown on the right (2pts)(10 points) 4. Bar magnets A and B are placed at a right angle to one another. Two compasses, X and Y, are placed so that they are equidistant from the two magnets, as shown. (Ignore the earth's field) i) The arrow in compass X indicates the direction in which the north Compass X pole of the compass is pointing. Indicate the north and south poles of Magnet Magnet A S B on the diagram. N Briefly but clearly, please explain. (3 pts) O Mag. B Compass Y ii) Which magnet is stronger? Please clearly circle ONE choice: A is stronger than B, or B is stronger than A or Both are equal in strength or There is not enough information to decide Briefly but clearly, please explain. (3 pts) iii) Compass Y is directly below the middle of magnet A and directly to the left of the middle of magnet B. Draw a single clear arrow in compass Y to show the direction in which the north pole of the compass would point. Briefly but clearly, please explain your work. (4 pts)5. Two different particles (labelled i and ii) have the same magnitude charge. They enter a region of uniform magnetic field (pointing out of the page, as shown) in a mass spectrometer. Their curved paths are shown. They both enter with the same velocity v. What conclusions can you draw (from physics principles) about the charge and mass of the two particles? Be fairly exhaustive in your answer (6 pts) ii BOYA XXXXX BZA XXXXX slope c a = 5 cm x X x x x Boz= -0.3 T Xxxxx x c = 0.08 T/s x x X xX Boz XXXXX t = 0 6. A circular loop of wire with finite resistivity and radius a is held fixed in the xy plane as shown in the diagram. The magnetic field in this region is aligned with the z-direction. The positive z-direction points out of the page. The field's z-component changes linearly with time as Bz(t) = Boz + c t , as shown in the plot. Boz and c are given in the figure. The left hand diagram shows the field at t = 0. A. What is the direction of the induced current in the loop at time t = ti when Bz crosses through zero? Explain how you obtained this direction (3 points) B. Calculate the magnitude of the EMF induced in the loop at time t =3 s. (3 points)The figure below refers to the next three problems. 7. The circuit shown below consists of a 9 V battery, three resistors, an ideal inductor and a switch. Assume that the switch has been open for a long time. R1 E 13 R2 R1 = 60 2 9V R3 R2 = 200 2 R3 = 300 0 L L = 0.01 H A) The switch is now closed at t = 0. Immediately afterwards, what is the current l3 flowing through resistor R3? (2 pts) B) A very long time after the switch has been closed, what is the current I1 through Ri? (2 pts) C) The switch is now suddenly opened. How long after opening the switch does it take for the current through the inductor to reach 1/e of its value just before the switch is opened? (2 pts)8. An ideal step-down transformer has a resistor with R = 6 2 attached to its secondary coil and its primary coil is plugged into a standard 120 VAC, 60 Hz outlet. The number of turns in the primary and secondary coils is 500 and 50 respectively. What is the average power drawn from the outlet? (6 points) 120 VAC 60 Hz R=60 MMA No = 500 N, = 50