[2019 DSE] Physics 物理 操題區

magnetix flux 個A只係睇B同A有overlapping嘅area
B=µnI條式只係consider緊B field INSIDE the solenoid(region highlighted in yellow)
黑色shadowed部分係無B field change
所以area只係拎A2

代數咪得囉，u =10

V=5

吓?

1.mu-mv=-mu
u-v=-u
v=2u
->impossible since u>v

2.mu-mv=-mv+mu
u-v=-v+u
->possible

3.mu-mv=mv
u-v=v
u=2v
->possible since u>v

加油啦
我淨係識力學

電學d式好難記
我諗住到時用公式表sub數算

我揀C呀 依份上年做既

而家仲溫得幾多

heat淨係識mc deltaT
wave好多都唔識

一路好走