1. The amount of energy transferred when 10 C of charge passes through a p.d. of 20 V is the same as the energy needed to raise a 2 kg mass through a distance X. What is the value of X?
Given gravitational acceleration = 10 ms^-2
The answer is 10 m.
2. A 1.5 V cell ‘pump’ out 10^16 electrons in 2 seconds. What is the power of the cell? (The charge carried by an electron is 1.6 x 10^-19 C).
The answer is 1.2 mW.
※請列明計算步驟※
Electricity & electromagnetism
2010-02-19 5:57 am
回答 (1)
2010-02-19 6:21 am
✔ 最佳答案
1. Energy tansferred to the 10 C charges = 10 x 20 J = 200 JGain in potential energy by the mass = 2gX
hence, 2gX = 200
X = 200/2g m = 200/20 m = 10 m
2. Energy delivered to each eelctron by the cell = 1.6 x 10^-19 x 1.5 J
Hence, total energy given by the cell to 10^16 electrons
= 10^16 x 1.6 x 10^-19 x 1.5 J
Power delivered by the cell = 10^16 x 1.6 x 10^-19 x 1.5 J/2 J/s = 1.2 x 10^-3 W = 3 mW
收錄日期: 2021-04-29 17:34:07
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