Exam 3 conceptual problems Name 1 In the figure a bar magnet moves away from the solenoid The induced current through the resistor R is A from b to a B from a to b C zero 1 2 Draw a circuit consisting of a battery connected to two resistors R1 and R2 in series with each 2 other and a capacitor C connected across the resistors A R1 R2 C B R1 C C R2 R2 R2 C D R1 R2 C 1 3 An ampere is a unit of electrical A current B resistance C pressure D all of these E none of these 3 4 When there is a change in the magnetic field in a closed loop of wire A a current is created in the loop of wire B electromagnetic induction occurs C a voltage is induced in the wire D all of these E none of these 4 5 Draw a circuit with a battery connected to four resistors R1 R2 R3 and R4 Resistors R1 and R2 are connected in parallel resistors R3 and R4 are connected in parallel and both parallel pairs 5 of resistors are connected in series A R1 R2 R3 R4 B R3 R4 R1 R2 C R1 R2 R3 R4 2 D R1 R3 R2 R4 6 Metal detectors like the ones used at airports are activated by A magnetic fields B electric fields C alternating current D electromagnetic induction 6 7 Outside a magnet magnetic field lines are conventionally drawn from A north to south B south to north C either way 7 8 While a magnet is moved toward the end of a solenoid a voltage difference is induced between the two ends of the solenoid wire The voltage difference would be larger if 8 A the bar magnet produced a stronger magnetic field B the solenoid contained more loops while having the same length C the speed of the magnet were increased D All of the above statements are true E Only two of the above statements are true 9 When a bar magnet is thrust into a coil of copper wire the coil tends to A repel the magnet as it enters B attract the magnet as it enters C both of these D neither of these 3 9 10 In the figure two parallel wires carry a current I in opposite directions A rectangular loop is midway between the wires The current I is decreasing The induced current through the resistor R is A from b to a B from a to b C zero 10 11 A 9 V battery is hooked up to two resistors in series One has a resistance of 5 and the other has a resistance of 10 Several locations along the circuit are marked with letters as shown in the figure Which statement is true 11 A The current at A is greater than the current at B which is equal to the current at C which is greater than the current at D B The current at A is equal to the current at B which is equal to the current at C which is equal to the current at D C The current at A is greater than the current at B which is greater than the current at C which is greater than the current at D 12 The primary source of electrons in an ordinary electrical circuit is A the power station generator B a dry cell wet cell or battery C the back emf of motors D the electrical circuit itself E none of these 4 12 13 In the figure a bar is in contact with a pair of parallel rails and is in motion with velocity A uniform magnetic field is present The induced current through the resistor R is A zero B from b to a C from a to b 13 14 The capacitance of a capacitor depends on A the energy stored in it B the charge on it C the potential difference across it D More than one of these E None of these 14 15 Electromagnetic induction occurs in a coil when there is a change in A electromagnetic polarity B voltage in the coil C electric field intensity in the coil D the coil s polarity E magnetic field intensity in the coil 15 16 If a magnet is pushed into a coil voltage is induced across the coil If the same magnet is pushed into a coil with twice the number of loops A the same voltage is induced B one half as much voltage is induced C four times as much voltage is induced D twice as much voltage is induced E none of these 16 17 Voltage can be induced in a wire by A moving the wire near a magnet B changing the current in a nearby wire C moving a magnet near the wire D Choices A B and C are all true E None of the above choices are true 17 18 On some early automobiles both headlights went out when one bulb burned out The headlights must have been connected in A parallel B haste C perpendicular D series 18 5 19 A circular wire ring is situated above a long straight wire as shown in the figure The straight wire has a current flowing to the right and the current is increasing in time at a constant rate Which statement is true 19 A There is an induced current in the wire ring directed in a counterclockwise orientation B There is an induced current in the wire ring directed in clockwise orientation C There is no induced current in the wire ring 20 In the figure a battery supplies a steady current to the solenoid on the left The two solenoids are moving toward each other The induced current through the resistor R is A from a to b B zero C from b to a 20 21 Magnetic field lines about a current carrying wire A circle the wire in closed loops B extend radially from the wire C Choices A and B are both correct D None of the above choices are correct 21 22 Which statement is correct A Voltage flows through an open or a closed circuit B Resistance flows though an open circuit C Current is the primary cause of voltage D Charge flows in a closed circuit 22 23 As more lamps are put into a series circuit the overall current in the power source A increases B stays the same C decreases 23 6 24 A conducting bar is free to slide horizontally on the rails of a conducting frame as shown in the figure A lightbulb is attached to the right end of the rails A spatially uniform magnetic field is oriented vertically perpendicular to the horizontal plane of the rails and bar Initially the bar is stationary The strength of the magnetic field begins increasing in time at a constant rate which induces a current through the bar frame and lightbulb The bar begins to move due to the magnetic force exerted on it Once the bar …
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