## PHYS208 Fundamentals of Physics II

### Hint for Ch. 33, 80P

Find the current through the circuit elements.
Next evaluate the voltage across each element.
Finally, the instantaneous power associated with an element will be the product
of the current and voltage at that time.

### Hint for Ch. 33, 81P

Find the extreme value by setting the derivative with respect to R to zero.
Calculus enthusiasts should prove that this yields a maximum value by
evaluating the second derviative...

### Hint for Ch. 33, 84P

a)Looking at the power dissipated by the resistor,
we want P_{max}/P_{min} = (I_{max}/I_{min})^{2} = (Z_{max}/Z_{min})^{2} = 5.

Solve for L in

5 = [R^{2}+X_{L}^{2}] / R^{2}.

b) Set up a resistive voltage divider and repeat the calculation above.

### Hint for Ch. 33, 85P

Evaluate the voltage phasor for each circuit element and combine appropriately to find the voltage
across combinations of elements.

"http://www.physics.udel.edu/~watson/phys208/exercises/hints/0511.html"

Last updated May 12, 1998.

Copyright George Watson, Univ. of Delaware, 1998.