SI Physics 222 Exam 2 Review – Monday October 31, 2011
1)
a) A long solenoid has 300 turns of wire per meter and has a radius of 3.0 cm. If the current in the
wire is increasing at a rate of 50 A/s, at what rate does the strength of the magnetic field in the
solenoid increase?
b) The solenoid is surrounded by a coil with 120 turns. The radius of this coil is 6.0 cm. What
induced EMF will be generated in this coil while the current in the solenoid is increasing?
2)
U Phys: In one form of Tesla coil, a long solenoid with length .5m and cross sectional area
10cm^2 is closely wound with 1000 turns of wire. A coil with 10 turns surrounds it at its center.
Find the mutual inductance.
3)
U Physics: A 300V dc power supply is used to charge a 25 microF capacitor. After the capacitor is
fully charged, it is disconnected from the power supply and connected across a 10mH inductor.
The resistance in the circuit is negligible. A) Find the frequency and period of oscillation of the
circuit. B) What is the total energy stored in the circuit?
4)
I have an Inductor, Resistor and Capacitor in series in a circuit. A) Given L=.2H and
C=3microfarads, what resistance will cause my current not to oscillate? If the resistor has
resistance of 10 Ohms, what is the frequency (Omega) of oscillations of capacitor charge?
For what resistance will my circuit oscillate at ½ of the undamped frequency?
5)
U Physics: In the series circuit of Fig. 31.13a, suppose R=300 ohms, L=60mH, C=.5 microF,
V= 50V, and omega = 10,000 rad/s. Find the reactances X_L and X_C, the impedance Z,
the current amplitude I, the phase angle “phi”, and the voltage amplitude across each
circuit element. If I am able to change the frequency, “omega”, how do I calculate omega
so that the current in the circuit is maximized?
6) Ames 88.5 KURE transmits radio waves at 79MHz frequency with power of 60kW. A) What is the
intensity of the wave on the other side of Ames 2km away? B) What is the wavelength of these
radio waves? C) Underwater in a pool 2km away, what is the speed, frequency, and wavelength
of the radio wave? D) What is the average magnitude of the wave’s magnetic field 2km away? E)
What is the maximum magnitude of the average magnitude of the waves EM field 2 km away?
7) Starting from underwater, I shine my light upwards out of the water with an angle of 20
degrees to the vector normal to the surface of the water. Just 1m above the water is a glass
case, 1 m thick, on top of which lies a diamond case 1 m thick, above which is water. A) What is
the angle of the light ray with the normal in each case? B) What is the speed of the light through
each of these 5 substances? C) What is the wavelength of light through each of these 5
substances? D) At what angle to the surface should I shine might light so that none of the light
exits the water (total internal reflection)?
8) U Phys: A converging lens has a focal length of 20cm. Find graphically the image location for
an object at each of the following distances from the lens. A)50cm B)20cm C)15cm D)-40cm
Determine the magnification in each case. Check your results by calculating the image position
and lateral magnification.