04 PP1 PHY

L.K.

完全唔明問咩..冇時間la  help...

piyopiyo

04年?=.=...點解我無印象ge...我前日先做完04 =.=...
1a. magnet... coil,,,,,,,commutator etc.
b. Blades turn -->coil inside turn in the magnetic field --> induced voltage -->current flows through the bulbs and lights up

2a. wavelength x frequency = speed
2b. X... energy lost , amplitude is smaller
2ci. speed = 6x10^3,,,total distance travelled:  0.0435m , 乘番 1000,,, 43.5 mm
2cii plot graph 自搞
2ciii. 睇到個graph 就做到,,,
2d. 題目話佢只係用 1個pulse,,,咁照理只有2個 pulse係CRO 度,1個reflected,1個放出去,但呢度有3個pulse, we can conclude that there's a crack inside the wall , the crack reflect the pulse

L.K.

turn in 點解???

piyopiyo

原帖由 L.K. 於 15-4-2008 14:16 發表
turn in 點解???

成句理解ar [[tk_30]]  turn in the magnetic field ar [[tk_30]]

L.K.

[[tk_30]] 咁成句點解...[[tk_30]]


仲有點解有crack就會...多左個...?[[tk_30]]

piyopiyo

原帖由 L.K. 於 15-4-2008 14:24 發表
[[tk_30]] 咁成句點解...[[tk_30]]


仲有點解有crack就會...多左個...?[[tk_30]]

個coil 係個magnetic field入面轉 [[tk_30]]  


個crack reflect左個pulse 咪多左個lor[[tk_30]]

L.K.

2b. X... energy lost , amplitude is smaller[[tk_35]]
[[tk_35]]  
energy lost 左去邊?
  
個crack reflect左個pulse 咪多左個lor

可唔可以用圖解.....

piyopiyo

原帖由 L.K. 於 15-4-2008 14:36 發表
2b. X... energy lost , amplitude is smaller[[tk_35]]
[[tk_35]]  
energy lost 左去邊?
  http: ...

energy lost to surrounding [[tk_38]]

係,多左個咪即係crack 左 lor[[tk_25]]

[S]【YU】

magnet... coil,,,,,,,commutator etc.

commutator is not required in this application, because the direction of current flow makes no difference.
We need a commutator only when we want to make a DC generator.
So the essential parts should be the coil and magnet only.

b. Blades turn -->coil inside turn in the magnetic field --> induced voltage -->current flows through the bulbs and lights up

Blades is connected to the coil under magnetic field in the motor.
Blades turns --> coil rotates and cuts the magnetic field --> voltage induced inside the coil (by right hand rule)
A complete circuit consisting the coil and the bulb allows current flow --> bulb light up

decrease in amplitide is caused by diffraction of wave, the recevier cannot collect 100% of the transmitted wave.



[ 本帖最後由 [S]【YU】 於 15-4-2008 16:32 編輯 ]

L.K.

原來係咁...
祝你身體健康