题干

电量为q的带电粒子以垂直于匀强磁场的速度V,从M点进入磁场区域,经偏转后,沿初速度方向运动距离为d,偏转距离为L从N点离开磁场,
如图所示,若磁场的磁感应强度为B,重力可忽略不计,那么

A:该粒子带正电

B:带电粒子在磁场中的运动时间t=d/V

C:洛仑兹力对带电粒子做的功是W=BqVL

D:带电粒子在N点的速度值也为V

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答案(点此获取答案解析)

D

同类题3

阅读短文,下列问题

C

Rob

     I don't think there is a solution to the environmental problems. The world population is now too large. We are going to run out of natural resources.

    Global warming shows us the effect that human beings have on the planet. Soon, millions of people will start leaving some parts of the world, because it will be impossible for them to live there any more, which in turn will create a whole new set of problems.

Louise

   The environmental situation is very serious, but I believe human beings can solve the problems.

   For example, we have already had clean ways of making electricity, like nuclear (原子能的) power and wind power.

   Besides, I think in the end, most people will want to help solve the problems. People just need to be made more aware of the problems and shown ways how they can help.

Michael

   We can now see that there has been a huge price to pay for the economic (经济的) development, because we have used a lot of natural resources and polluted the Earth.

   Of course, we can do many things to protect the Earth. For example, we can recycle (回收利用) or drive cars that pollute a bit less, or even use fewer plastic bags. However, I really don't know if these small things are going to be enough to solve the problems.

Rob

     I don't think there is a solution to the environmental problems. The world population is now too large. We are going to run out of natural resources.

    Global warming shows us the effect that human beings have on the planet. Soon, millions of people will start leaving some parts of the world, because it will be impossible for them to live there any more, which in turn will create a whole new set of problems.