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[Phy] Electrical Power and Domestic Electricity

Electrical Power and Domestic Electricity

1. The rating of an air-conditioner is '200V, 60Hz, 2500W'. Explain what is meant by (a) 200V; (b) 60Hz; and (c) 2500W.

2. Explain how the following designs ensure our safety.
(a) In a plug, the earth pin is longer than the live pin and the neutral pin.
(b) A fuse is connected to the live wire instead of the neutral wire.
   
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[隱藏]
1. pls check definetion
2.(a) what is the usage of earth wire?
(b) Think whether current pass through your body if you touch live or neutral wire
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[quote]原帖由 Light2012 於 2014-12-17 11:08 PM 發表
1. The rating of an air-conditioner is '200V, 60Hz, 2500W'. Explain what is meant by (a) 200V; (b) 60Hz; and (c) 2500W.

Sol: Rating: If the air-conditioner is connected to a 200 V r.m.s. supply, the power supplied to the air-conditioner is 2500W.
       Frequency = 60 Hz means in 1 second, the current changes direction 100 times.

2. Explain how the following designs ensure our safety.
(a) In a plug, the earth pin is longer than the live pin and the neutral pin.

Sol: It ensure that the Earth pin is connected to the ground before the live and neutral pin. Therefore, in case there is current leakage, the current will flow through the Earth wire instead of human body touching the metal case.

(b) A fuse is connected to the live wire instead of the neutral wire.

Sol: It ensure that when the fuse blown, the electrical appliance is disconnected from "High Potential"!!! The change of getting electric shock is lower!

Remember, it is nothing to do with the complete circuit or not!
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