物理高手..幫幫忙

如果你的R1被燒壞 => 整個的電路就變得不完整

R1被燒壞 其實等於你切斷了一條電線
既然電線俾切斷,整個的電路就變得不完整
自然沒有任何的電流流經這個的電路
加上你的是串聯
沒有電流流經r1 = 沒有電流流經r2
因為佢地是同用一條電線連接的
所以答案係0 A

如電源電壓為u=90v R1=15歐姆 R2=30歐姆

Using Ohms' Law,
90 = (R1).I + (R2).I ----------------- (1)
where I is the current through the circuit

i.e. I = 90/(R1+R2)

1)問如R1被燒壞,通過R2的電流是多少?2)如r2被短路,將發生什麼情況?

When R1 is burnt, its resistance becomes infinite, thus
I = 90/(infinity+R2) = 90/infinity = 0 ampere

2)如r2被短路,將發生什麼情況?

When R2 is short-circuit, its resistance becomes zero,
hence, equation (1) becomes,
90 = (R1).I + (0).I = (R1).I
but (R1).I is the voltage across R1 which, according to the above equation, is 90 volts.

係串聯

2009-06-07 19:28:08 補充：
都係唔明..

串聯定並聯嫁？!

2009-06-07 19:27:06 補充：
因為係串聯 ,而且R1被燒壞了,R2的電流是0A。