Download Chapter 1 Due Monday 4/9 at 4 pm.

ENGR&204 Spring 2012 Homework # 1 Due Monday 4/9 at 4 pm
1) A portable CD player uses 2 AA batteries in series to produce 3.0 v to the player circuit. The two AA
cells store a total of 100 W.s of energy. If the player is drawing a constant current of 2.0 mA from the
battery pack, how long will the CD player operate at normal power?
2) The power supplied by a certain battery is a constant 6.0 W over the first 5 minutes, zero for the next
2 min, a value that increases linearly from zero to 10 W during the next 10 minutes, and a power that
decreases linearly from 10W to zero in the following 7.0 minutes. A) What is the total energy in
Joules expended during this 24 minute interval? B) What is the average power in W during this time?
(
)
3) Let
for the circuit shown. A) What power is
being absorbed by the circuit element at t = 5 ms? B) What is the energy delivered to the element in
the interval 0 < t < ∞ ?
i
v
4) Are all of the voltages and currents in the circuit shown correct? Do a power check to find out: Total
power used must equal total power supplied.
5) A two terminal element absorbs an energy w as shown in the graph below. If the current entering the
positive terminal is i = 100 cos(1000t) mA, find the element voltage at t = 1 ms and at t = 4 ms.
6) A small rocket uses a two element circuit as shown in the figure to control a jet valve from the point
of liftoff at t = 0 s to the rocket runs out of fuel at 1.0 minute. The energy that must be supplied by
element 1 for the 1 minute period is 40 mJ. Element 1 is a battery to be selected. It is known that i(t)
= De-t/60 mA for t ≥ 0, and the voltage across the second element is v2 = Be-t/60 volts for t ≥ 0. The
maximum possible magnitude of the current, D, is limited to 1.0 mA. Find the required constants D
and B and describe the required battery. Hint: find the energy supplied by the first element for the 1
minute period…