Download 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: A pulsed laser emits 0.135J of energy in a pulse that lasts 15ns and it is focused over
an area of 2.25mm2. Calculate the amplitude of its magnetic and electric fields.
P3: 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.
P4: 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.
P6: Image formation by a converging lens. We buy a magnifying glass that has a
power of 2.5 D. If we place an object 30.0 cm away from the lens, where is the image
formed (find d i ) and what kind of image is it (real, virtual, upright, inverted)?
P5: 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.
P7: In the following example of a concave mirror find the position of the image and
describe it (virtual, real, upright, inverted, larger, smaller, etc)
P8: You want to steer a beam of electrons (charge=-1.6x10-19C) as shown in the figure.
Indicate the direction of the magnetic field that will do this for you.
P9: You are standing 4.0 m from a convex security mirror in a store. Your image looks
0.35 times your actual size. What is the focal length (f) of the mirror?
P10: You point a laser beam to the surface of a fish tank as shown in the figure. Find the
angle β at which the beam exits through the side of the tank (you can ignore the effect of
the glass wall). The index of refraction of water is 1.33
P11) A nearsighted person has the far point at 0.66m (only objects closer than 66cm in
front of the eye are seen clearly). Calculate the focal length of a corrective lens that will
put the image of a very distant object (do=∞) at the far point.
Ignore the distance eye-lens.
[Hint: Remember the sign conventions]
------------------------------------------------------------------------------------------Phys 2025 Extra Problems for Calculus based Physics
P13) A convergent lens of focal length f1=40cm is placed 15 cm in front of a divergent
lens of focal length f2=-120cm. Calculate the final position of the image generated by this
combination if the object is 80cm to the left of the convergent lens.
P14: An experiment done with a sample of doped silicon (with holes as carriers of
electricity) as shown in the schematic figure below. Calculate the Hall voltage if the drift
velocity of the holes is v=0.3 m/s, the magnetic field is 1.5T and the width of the sample
is 2.5 cm.
P15: a) When calculating the Poynting vector, what is the meaning of the magnitude of
the vector and what is the meaning of its direction?
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b) How do you use the Hall Effect to tell the sign of the charge of the current carriers?
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