Exam 3 conceptual problemsName___________________________________1)In the figure, a bar magnet moves away from the solenoid. The induced current through theresistor R is:A)from b to aB)from a to bC)zero1)2)Draw a circuit consisting of a battery connected to two resistors, R1and R2, in series with eachother and a capacitor C connected across the resistors.A)R1R2CB)R1CR2C)R2R2CD)R1R2C2)13)An ampere is a unit of electricalA)current.B)resistance.C)pressure.D)all of theseE)none of these3)4)When there is a change in the magnetic field in a closed loop of wireA)a current is created in the loop of wire.B)electromagnetic induction occurs.C)a voltage is induced in the wire.D)all of theseE)none of these4)5)Draw a circuit with a battery connected to four resistors, R1, R2, R3, and R4. Resistors R1andR2are connected in parallel, resistors R3and R4are connected in parallel, and both parallel pairsof resistors are connected in series.A) R1R2 R3R4B) R3R4R1R2C)R1R2R3R45)2D) R1R3 R2R46)Metal detectors, like the ones used at airports, are activated byA)magnetic fields.B)electric fields.C)alternating current.D)electromagnetic induction.6)7)Outside a magnet, magnetic field lines are conventionally drawn fromA)north to south.B)south to north.C)either way7)8)While a magnet is moved toward the end of a solenoid, a voltage difference is induced between thetwo ends of the solenoid wire. The voltage difference would be larger ifA)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.8)9)When a bar magnet is thrust into a coil of copper wire, the coil tends toA)repel the magnet as it enters.B)attract the magnet as it enters.C)both of theseD)neither of these9)310)In the figure, two parallel wires carry a current I in opposite directions. A rectangular loop ismidway between the wires. The current I is decreasing. The induced current through the resistor Ris:A)from b to aB)from a to bC)zero10)11)A 9 V battery is hooked up to two resistors in series. One has a resistance of 5 Ω, and the other hasa resistance of 10 Ω. Several locations along the circuit are marked with letters, as shown in thefigure. Which statement is true?A)The current at A is greater than the current at B, which is equal to the current at C, which isgreater 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 equalto the current at D.C)The current at A is greater than the current at B, which is greater than the current at C, whichis greater than the current at D.11)12)The primary source of electrons in an ordinary electrical circuit isA)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 these12)413)In the figure, a bar is in contact with a pair of parallel rails and is in motion with velocity ν. Auniform magnetic field is present. The induced current through the resistor R is:A)zeroB)from b to aC)from a to b13)14)The capacitance of a capacitor depends onA)the energy stored in it.B)the charge on it.C)the potential difference across it.D)More than one of theseE)None of these14)15)Electromagnetic induction occurs in a coil when there is a change inA)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 pushedinto 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 these16)17)Voltage can be induced in a wire byA)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 headlightsmust have been connected inA)parallel.B)haste.C)perpendicular.D)series.18)519)A circular wire ring is situated above a long straight wire, as shown in the figure. The straight wirehas a current flowing to the right, and the current is increasing in time at a constant rate. Whichstatement is true?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.19)20)In the figure, a battery supplies a steady current to the solenoid on the left. The two solenoids aremoving toward each other. The induced current through the resistor R is:A)from a to bB)zeroC)from b to a20)21)Magnetic field lines about a current-carrying wireA)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 sourceA)increases.B)stays the same.C)decreases.23)624)A conducting bar is free to slide horizontally on the rails of a conducting frame, as shown in thefigure. A lightbulb is attached to the right end of the rails. A spatially uniform magnetic field isoriented vertically (perpendicular to the horizontal plane of the rails and bar). Initially the bar isstationary. The strength of the magnetic field begins increasing in time at a constant rate, whichinduces a current through the bar, frame, and lightbulb. The bar begins to move due to themagnetic force exerted on it. Once the bar begins to move, the brightness of the lightbulbA)increases.B)stays the same.C)suddenly drops to zero.D)decreases.24)25)A magnet, with its north pole pointed downwards, is falling down directly above a wire loop. Asthe magnet approaches the wire loop (before it passes through the loop),A)an induced current flows through the wire loop, in a counterclockwise orientation (as seenfrom above).B)no current flows through the wire loop.C)an induced current flows through the wire loop, in a clockwise orientation (as seen fromabove).25)26)Like kinds of magnetic poles
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