## Hour Exam #2

## October 13, 1999

## Statistics:

## High: 100 (2!)

## Mean: 82

## Low: 50

1. (20.12) An electron moves in a circular path, perpendicular to a magnetic field of B = 1.25 T, with a a speed of 1.2 x 10^{4}m/s. What is the radius of the electron's circular path?This is homework

problem 20.12, verbatim.UseBackto return here.

2. (21.7) A rectangular loop has dimensions of 2.0 cm by 3.0 cm and is initially between the poles of a large magnet, where the magnetic field strength is B = 0.050 T. The loop is oriented so the normal to the plane of the coil lies parallel to the direction of the magnetic field. The coil is removed from that region to a region with no magnetic field in 0.15 seconds. What is the average induced emf?This is homework

problem 21.7, verbatim.UseBackto return here.

3. (22.7) An electric light, connected to an ordinary 120 V AC wall outlet, uses 60 W of power. What are

a) the rms current through the light,

b) the resistance of the light, and

c) the maximum and minimum instantaneous values of the power and of the current?This is homework

problem 22.7.UseBackto return here.

4. (22.37)Consider a series RCL circuit with R = 80 , C = 15 F, L = 250 mH connected to a 12 V, 120 Hz AC source.

a) Calculate the reactances X_{C}and X_{L}.

b) What is the total impedance?

c) What current flows through the circuit?This is the first three parts of homework

problem 22.37.UseBackto return here.

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