Phy mock paper

http://imm.io/YrXS

求解答,謝謝。
Update: for question 2:
Peter brought a rice cooker that operates at 110 V from Japan to HK. He connects the rice cooker to the mains through a transfomer that steps down the voltage from 220 V to 110 V. he coonects an ammeter to the circuit to study the cuurent drawn by the rice cooker.
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