phsics --- 電

Q6
Resistance = 240^2/100 ohms = 576 ohms

Energy consumed in 10 minutes
= 100 x 10 x 60 J = 60 000 J
since 1 kW-h = 3 600 000 J
hence, energy soncumed in 10 minutes = 60 000/3600000 kWh = 0.0167 kWh
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Q4
(a) electric field intensity = 2000/0.025 V/m = 80000 V/m

(b) Force = 1.6x10^-19 x 80000 N = 1.28x10^-14 N

(c) The electric field lines are uniformly spaced vertical lines pointing from the upper plate towards the lower plate. This indicates an uniform electric field.

圖片參考：http://x64.xanga.com/781c876245434192188377/b148098474.jpg

應該係
Q6
P = V^2 / R, so. R = V^2 / P
R = 240^2/100 watt = 576 ohms



Energy consumed 100w in 10 minutes
= 100w = 0.1Kw
=10 minutes = 0.1666667 hrs
so. 0.1 x 0.1666667 = 0.01666667Kw/h = 16.66667w/h

呢題冇問題
Q4
(a) electric field intensity = 2000/0.025 V/m = 80000 V/m

(b) Force = 1.6x10^-19 x 80000 N = 1.28x10^-14 N

(c) The electric field lines are uniformly spaced vertical lines pointing from the upper plate towards the lower plate. This indicates an uniform electric field.