班級:光電一乙
學號:498L0106
姓名:高柏翔
98學年度第2學期物理Chap17作業:
1. A certain conductor has 7.50 × 1028 free electrons per cubic meter, a
cross-sectional area of 4.00 × 10−6 m2, and carries a current of 2.50 A. Find the
drift speed of the electrons in the conductor.
Q=(n
)q
=>I
=(n
)q
2. A 1.00-V potential difference is maintained across a 10.0-Ω resistor for a
period of 20.0 s. What total charge passes through the wire in this time
interval?
V=IR
=>I=
Q=It=0.1
3. A potential difference of 12 V is found to produce a current of 0.40 A in a
3.2-m length of wire with a uniform radius of 0.40 cm. What is (a) the
resistance of the wire? (b) the resistivity of the wire?
(a)
= =
(b)
R＝ρ
ρ＝R
4. A metal wire has a resistance of 10.00 Ω at a temperature of 20°C. If the
same wire has a resistance of 10.55 Ω at 90°C, what is the resistance of the
wire when its temperature is −20°C?
10.55=10[1+
10.55=X[1+
X=
5. How much does it cost to watch a complete 21-hour-long World Series on a
180-W television set? Assume that electricity costs $0.070/kWh.
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