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物理題目,請高人詳細解釋(急急)
發問:
一個未知的正電粒子自水平方向射入水平放置的兩平行金屬板間,己知兩金屬板兩端電位差為V,兩皮間距離d,平行板長度為L,若未知的正電粒子的運動軌跡維持一直線,則1未知的荷質比?2改以電子射入,而發現其垂直偏移距離為Q時,則入射電子的速度?
1. Let q be the charges on the particle and m be its mass, hence, electric force acting on the particle = q.E, where E is the electric field intensity But E = (V/d), hence, force acting on the particle = q(V/d) When the particle travelled in a straight line, the electric force balanced the weight of the particle, i.e. q(V/d) = mg, where g is the acceleration due to gravity q/m = g.d/V 2. Let e be the electronic chagre and m be its mass. Consider the vertical motion of the electron, use equation of motion: s = ut + (1/2)at^2, with u = 0 m/s, a = eE/m = (e/m).(V/d), s = Q i.e. Q = (1/2).(e/m).(V/d).t^2 ----------------- (1) Consider the horizontal motion, L = v.t, where v is the initial speed of the electron i.e. t = L/v substitute t = L/v into (1), Q = (e/2m).(V/d).(L/v)^2 solve for v gives v = square-root[eVL^2/(2mdQ)]
其他解答:
物理題目,請高人詳細解釋(急急)
發問:
一個未知的正電粒子自水平方向射入水平放置的兩平行金屬板間,己知兩金屬板兩端電位差為V,兩皮間距離d,平行板長度為L,若未知的正電粒子的運動軌跡維持一直線,則1未知的荷質比?2改以電子射入,而發現其垂直偏移距離為Q時,則入射電子的速度?
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最佳解答:1. Let q be the charges on the particle and m be its mass, hence, electric force acting on the particle = q.E, where E is the electric field intensity But E = (V/d), hence, force acting on the particle = q(V/d) When the particle travelled in a straight line, the electric force balanced the weight of the particle, i.e. q(V/d) = mg, where g is the acceleration due to gravity q/m = g.d/V 2. Let e be the electronic chagre and m be its mass. Consider the vertical motion of the electron, use equation of motion: s = ut + (1/2)at^2, with u = 0 m/s, a = eE/m = (e/m).(V/d), s = Q i.e. Q = (1/2).(e/m).(V/d).t^2 ----------------- (1) Consider the horizontal motion, L = v.t, where v is the initial speed of the electron i.e. t = L/v substitute t = L/v into (1), Q = (e/2m).(V/d).(L/v)^2 solve for v gives v = square-root[eVL^2/(2mdQ)]
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