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  1. 如圖中所示,若電池有內阻,可以考慮加一個電阻 r,在電池旁以方便計算。 圖片參考:http://hk.geocities.com/namsm4e/p0125.jpg 所以電路的 總電阻為 10 + r,電壓為 3v,電流為 0.214A,依歐姆定律 V = I R 3 = 0.214(10 + r) r = 4.0Ω 其實這...

  2. ... the answer is D All of them could actually be show in ray diagram. 5. when a glass block put between the lens and S, we could consider...

  3. ...positive.) So comparing the solid waveform (representing the moment shown in the question) and the dotted waveform (representing the moment a little...

  4. conservation of momentum initial momentum = mu final momentum = mv1+2mv2 u = v1 +2v2 using above forumla, eliminating ans A conservation of kinetic energy: final energy must be less than initial energy initial energy = 1/2 m u^2 final energy = 1/2 m v1^2 + m v2^2 u^2 = v1^2 + 2v2^2 ans B & D...

  5. ... emf is related to the rate of change of magnetic flux linkage as shown in the equation below: 圖片參考:http://i117.photobucket.com/albums/o61/billy_hywung...

  6. Ans: B (1) is wrong. d.c. current cannot be adopted in transformer as d.c. current in the primary current produce constant magnetic field (i.e. no magnetic flux change) inducing zero e.m.f. in the secondary coil. energy cannot be transfer, let alone its step down process. (2...

  7. It should be B, (1) and (2) (1), Work done = Fs = area under the graph = xy /2 J So, (1) is correct. (2). By Newton's 2nd law of motion F = ma From the graph, F is +ve throughout the journey, so acceleration...

  8. Q1 冇左figure 5.2. Q2 actually, to see the movement direction of particle in wave is very easy. when the wave travelling toward right, just see the point in the left hand side of this point. For Q, it is in 0.4cm RHS to the relative position, and in the next step, it will be same as...

  9. Consider the horizontal component Horizontal speed of the ball =10cos30* =8.66 m/s Consider the vertical component Initial vertical speed of the ball =10sin30* =5 m/s The ball will experience a downward acceleration due to gravity. By the law of conservation of momentum...

  10. Reslove vertically: s=ut+a(t*2)/2 -500= -10(t*2)/2------------(u=0) t=10s Reslove horizontally: s=ut-----------------(a=0) d=200t d=2000m