[2019 DSE] Physics 物理 操題區

比起其他科好似算淺左
考完咁多日 大家一致認為會深過2018

Mc炒左

Mc 錯6 **無望

想問25條點解係B

點解25係b 唔係c

L2 short circuit= no resistance
所以current唔會行去L3
L3唔會着
Hence (2) is wrong

個electromagnet會轉polarity?

When ac is used, the current in the solenoid and the coil will change together. Hence, the magnetic force acting on the coil will not change

但唔會有個mg向下咩

粒波係張枱上面

有無人1aii 答咗less ice

For (2)

Phosphorus-32 half life>>>14.3 days
Carbon-11>>>20.3 min

Decay constant=ln2/half life
Hence decay constant is inversely proportional to half life, ie half life increases>>decay constant decreases

Decay constant of phosphorus-32 should be smaller than carbon-11

佢受完力之後飛起咗 唔知我有冇理解錯