【简答题】Do advantages in technology make the world better or worse? I believe that advances in technology make the world better. The following are three reasons that I have to support my opinion. ( _____ )(1....
【简答题】在霍尔效应中,导体长4.0 cm,宽1.0 cm,厚1.0×10-3cm,沿长度方向载有3 A的电流,当磁感应强度为1.5 T的磁场垂直地通过该导体时,产生1.0×1 0-5V的横向霍尔电压V(在宽度两端),如图所示。试求: (1)载流子的漂移速率; (2)每立方厘米载流子的数目; (3)设载流子是电子,就一给定的电流和磁场方向,确定霍尔电压的极性。
【单选题】下 列哪一项不属于神经-肌接头处兴奋传递的特点( )
【简答题】在霍尔效应中,导体长4.0cm,宽1.0cm,厚1.0×10 -3 cm,沿长度方向载有3A的电流,当磁感应强度为1.5T的磁场垂直地通过该导体时,产生1.0×10 -5 V的横向霍尔电压V(在宽度两端),如图所示。
【简答题】如图所示的坐标平面内,y轴左侧存在方向垂直纸面向外、磁感应强度大小B 1 =0.20T的匀强磁场,在y轴的右侧存在方向垂直纸面向里、宽度d=12.5cm的匀强磁场B 2 ,某时刻一质量m=2.0×10 -8 kg、电量q=+4.0×10 -4 C的带电微粒(重力可忽略不计),从x轴上坐标为(-0.25 m,0)的P点以速度v=2.0×10 3 m/s沿y轴正方向运动.试求 要使微粒不能从右侧磁场边...
【单选题】Which of the following would the author most probably agree?
A.
Not all of the developing world's most successful companies are globalizing.
B.
Companies venturing abroad most eagerly are the most successful at home.
C.
Local dynamos are the most successful firms all over the world.
D.
Globalizing is not good for companies in emerging economies.
【简答题】如图所示的坐标平面内,y轴左侧存在方向垂直纸面向外、磁感应强度大小B 1 =0.20T的匀强磁场,在y轴的右侧存在方向垂直纸面向里、宽度d=12.5cm的匀强磁场B 2 ,某时刻一质量m=2.0×10 -8 kg、电量q=+4.0×10 -4 C的带电微粒(重力可忽略不计),从x轴上坐标为(-0.25 m,0)的P点以速度v=2.0×10 3 m/s沿y轴正方向运动.试求 微粒在y轴左侧磁场中运动...