關於簡單的物理問題

1. 1. In the figure, a 4-V battery is connected to a 3-Ω resistor. The voltmeter is ideal and it reads 3 V. If the ammeter has an internal resistance of 0.1Ω, which of the following deductions is / are correct?
(1) The current passing through the resistor is 1 A.
(2) The voltage across the ammeter is 1 V.
(3) The battery has an internal resistance of 0.1Ω.
A. (1) only
B. (1) and (2) only
C. (1) and (3) only
D. (2) and (3) only

http://i617.photobucket.com/albums/tt257/michaelcoco_/7-1.jpg

2. 2. In the circuit shown, a ‘10 V, 40 W’ light bulb is operated by 220-V mains electricity through a step-down transformer. The turn ratio of the transformer is 22:1 and the transformer’s efficiency is 80%. Which of the following statements is / are correct?
(1) The primary current is 0.227 A.
(2) The current through the bulb is 4 A.
(3) The secondary voltage of the transformer is 8 V.
A. (1) only
B. (2) only
C. (1) and (2) only
D. (1) and (3) only

http://i617.photobucket.com/albums/tt257/michaelcoco_/8.jpg

3.




1st statement

2nd statement


When a 3-V cell with internal resistance 1Ω delivers 1 A of current, the useful power output of the cell is 1 W.

When a current I passes through a resistance R, its power consumed is I2R.

The answer is D.

※試列明計算步驟及各點對與錯之原因※