→ smhead:1&2題磁場是不是打成電場了？ 07/05 11:06
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作者: WeiFanL (WeiFan) 看板: TransPhys
標題: Re: [考古] 中原考古題幾題
時間: Sat Jul 21 08:14:31 2012
※ 引述《hugesox (阿銘)》之銘言：
: _ _ ^ _
: 1.若空間任意點電場B=Ar x k 其中r是該點的位置向量,A是個常數,則經過一個位於xy平面,
: 以原點為中心,半徑為R的圓圈的淨電流為?
0,因為磁通量為0，原因是 電磁場B永遠平行XY平面
: 2.若一平面電磁波電場振幅為100V/m,則其電廠振幅為?T
= =，答亦所問，但是單位是T，你是想問電磁場吧?
答案是100/C
: 3.總質量為M的火箭,以30度仰角發射,初速V射出,達最高點時與發射原點的水平距離
: 為D,並於最高點分成2個等質量的部份,其中一部份自由落下,請問另一部份落地時,
: 與發射點的水平距離為?
(1)設V'為所求部分之初速
MVcos30=MV'/2
V'=√3V(水平方向)
(2)設所求部分之飛行時間為t
gt=V/2
由(1).(2)得知
D=(√3/2)V^2/g
: 4.Consider the RC circuit that has been
: disconnected for a very long time before switching
: on at the time t = 0.
: (a) Find the voltage across the capacitor right after
: switching on the switch S.
0 V
: (b) Find the initial current I(0) that flows through the
: resistor 4歐姆t = 0
5/4 A
: (c) Find the current I(t) that flows through the
: resistor 4歐姆 t > 0
I(t)=5/4 *exp(-4t/3) + 5/12*[1-exp(-4t/3)] A
: (d) Find the current I(t) that flows through the
: resistor 8歐姆 t > 0
I(t)=5/12 *[1-exp(-4t/3)] A
: 圖在下
: _____電阻(4歐姆)____/ S______________
: | | |
: | | |
: | 電阻(8歐姆) 電容(0.5F)
: 電池(5V) | |
: | | |
: |___________________________|_________|
: 5.Consider a system of 1 mole of
: oxygen gas at temperature 1000 oC. The oxygen
: gas undergoes free expansion and triples its volume.
: Find the entropy change in the free expansion.
△S=nRln(Vf/Vi)
=8.314*In3
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_ _ ^ _
1.若空間任意點電場B=Ar x k 其中r是該點的位置向量,A是個常數,則經過一個位於xy平面,
以原點為中心,半徑為R的圓圈的淨電流為?
2.若一平面電磁波電場振幅為100V/m,則其電廠振幅為?T
3.總質量為M的火箭,以30度仰角發射,初速V射出,達最高點時與發射原點的水平距離
為D,並於最高點分成2個等質量的部份,其中一部份自由落下,請問另一部份落地時,
與發射點的水平距離為?
4.Consider the RC circuit that has been
disconnected for a very long time before switching
on at the time t = 0.
(a) Find the voltage across the capacitor right after
switching on the switch S.
(b) Find the initial current I(0) that flows through the
resistor 4歐姆t = 0
(c) Find the current I(t) that flows through the
resistor 4歐姆 t > 0
(d) Find the current I1(t) that flows through the
resistor 8歐姆 t > 0
圖在下
_____電阻(4歐姆)____/ S______________
| | |
| | |
| 電阻(8歐姆) 電容(0.5F)
電池(5V) | |
| | |
|___________________________|_________|
5.Consider a system of 1 mole of
oxygen gas at temperature 1000 oC. The oxygen
gas undergoes free expansion and triples its volume.
Find the entropy change in the free expansion.
以上 謝謝各位!
感激不盡
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