page 442-4
1-3. Use Ohm's law
4. For cells in series, emf's add algebraically
for total emf output.
5. (a) refer to p 414 for symbols. (b) for
resistors in series, simply add together
(c) Ohm's law.
7. (a) Remember definition of the ampere.
Watch the units. (b) Use fundamental charge
of electron.
8. Use Ohm's law to find current. What do
we know about current in a series circuit?
(b) Find total resistance. (c) Apply Ohm's
law to each resistor.
9. Find total resistance and use Ohm's law.
(b) Refer to p 422 and picture on 423 to
figure battery arrangement.
10. Resistance laws for series and parallel.
13. Three parallel branches with one resistor
in each, use parallel resistance rule; (b)
Calculate the voltage drop across the one
resistor whose current you know. What do
we know about voltage across parallel circuit
elements? Use this information to find source
voltage and current through the other resistors.
20. (b) Collapse parallel section into one
equivalent resistance, then combine with
remaining series resistance. (c) Calculate
current output of battery using total resistance
and Ohm's law. Now find voltage drop across
series resistor. Voltage drop across parallel
combination can now be found and used to
find branch currents through each parallel
resistor.
21. Start with R4 and R5. What do you know about these parallel resistors?
Use Kirchhoff's junction rule to analyze
currents around junctions and the loop rule
to figure voltage drops. Work back and forth
using all your tools and you can figure this
out.
22. Similar to 21, but more of a challenge
because of R2 and R5. If you can figure this out, you're ready
for any resistor combination.
12.(a) Find output voltage of battery, then
use Ohm's law (b) Use resistivity equation;
watch the units.
15. (a) Look up resistivity of 18 gauge wire
in table, then use resistivity equation p.
436 (b) Determine how length and resistance
are related.
page 457-8
3. (a) Use power equation 6, p452 (b) Use
equation 7 p 453
4.(a) Remember work done equals energy used;
be careful of units (b) convert part a into
kW hrs
6. Similar to #4
7. Electrical energy is converted to heat
energy in the iron. Conservation of energy
tells us the quantities must be the same.
Calculate the power output of the iron, then
find the energy used in 45 min (watch the
units). Now convert to kcal (chapter8, p
170)
13. Find the current, convert to electrons/s,
then calculate for a whole day (24 hrs)
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