如图所示，在倾角为α的光滑斜面上，置一通有电流I，长为L，质量为m的导体棒．
(1)欲使导体棒静止在斜面上，所加匀强磁场的磁感应强度B的最小值为__________，方向__________；
(2)欲使棒静止在斜面上，且对斜面无压力，所加匀强磁场的磁感应强度B为__________，方向__________。
(1)
；垂直于斜面向上
(2)mg/IL；水平向左
I often go to a shopping center with my mother. The shopping center is new and__1__. There are lots of great things there. There are __2__and food. There are many people there. ___3__do many people come here to buy things? Do you know? Let me tell you. The things there are good and at a very great price. The ____4__there are nice and friendly. So I buy a T-shirt ___5__ red for only 2 dollars. My sister Mary has a yellow sweater. It’s very nice. But it’s too small. She ___6____a new one. She goes to the shopping center with us on Sunday. Because she doesn’t go to __7____ that day. There are many clothes on__8____. They are very nice. They are in all___9___. There are red, black, red and blue ones. She likes a blue sweater very much. __10____it’s too big. At last, she takes a green sweater for only 0 dollars.
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