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Name____________________________ Reading Guide for Ch. 17 Direct Current
1. Read p. 615-617. Define:
a. an Ampere
b. current
c. resistance
2. If electricity is made of negative electrons, and if protons are locked
in the nucleus and cannot flow, why is current defined as the flow of
positive charge.
3. Recalculate the current in example 17.1 if 4.0 microCoulombs of
charge were transported in 300 ms.
Read p. 617-622
4. Explain how batteries work
5. What 2 metals would you use from table 17.1 to make the highest
voltage battery cell?
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What would the voltage of 1 such cell be?
How could you exactly double the voltage?
6. “Electromotive force” (EMF) is almost synonymous with voltage.
Explain the difference between EMF and voltage.
7. Define
a. load
b. direct current
c. amp-hour rating
8. People talk about devices “using up” electricity, but the text says that
electricity is never “consumed”. Explain this apparent contradiction.
Read “Resistance’ pp. 624-627
9. Write the equation for Ohm’s Law and define each variable.
10. Define
ammeter
voltmeter
11.Use figure 17.17 to explain in your own words how an ammeter and a
voltmeter are connected differently in an electrical circuit.
12.Recalculate example 17.4 to find the voltage if the current were 700
Amps and the resistance were 100 microhms.
Read “Resistivity” pp. 627-631.
13.Copy formula 17.4 and explain what each variable means.
Read 631-634
14.Give 3 formulas for calculating electrical power and tell what all
symbols mean.
15.Tell how you would increase or decrease V, I or R to get the
maximum power running through a circuit.
16.Recalculate the power through each circuit element in ex 17.7 if the
current were doubled to 10 Amps and the voltage of the top battery
were doubled to 24 volts.