# Exam 2 Practice ```Phys 1215, Second Test Practice
P1: Induction. Indicate the direction of the induced current in the loop in each of the
following cases:
P2: Find the magnetic field at point “P” produced by the two long straight current
carrying wires shown in the figure. Make sure to answer with magnitude and direction.
P3: Find the magnetic force on a proton coming towards our planet at a speed of
4x105m/s if the magnetic field of the Earth is 1.5x10-5T at that point and it is
perpendicular to the velocity of the proton (as shown in the figure). Answer with
magnitude and indicate the direction of the force in the figure below.
P4: A circular loop of wire of diameter 1.05m is located in a region where the magnetic
field is 0.225T and perpendicular to the plane of the loop. You pull the wire reducing the
diameter of the loop to 0.95m in 5 seconds. Find the average emf produced by this
change.
P6: A series RL circuit has R of 25 Ω, L of 12 H. The source voltage is 8.0 V.
Find the maximum current in the circuit after the switch is closed.
Find the time constant of the RL circuit.
Find the current in the circuit 1.2 seconds after the switch is closed.
P7) Find the power delivered by the voltage source. The voltage is given in RMS
voltage. Find the voltage across resistor, R1.
P8) Write down the equations you would use to solve for the currents in each branch of
the circuit. Draw the directions of the current on the diagram.
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