-
All right. So please raise your hand now if you think there'll be sufficient energy to eject electrons from the metal surface?
好的，如果你们认为,有足够的能量从金属表面,射出电子请举手？
-
Intensity, if we increase the intensity, we're not increasing the energy in each photon, we're just increasing the number of photons that we're shooting out of our laser, whatever our light source is.
强度，如果我们增加强度，我们增加的不是,每个光子的能量，我们增加的仅仅是,从我们激光源射出的光子数，无论我们的光源是什么。
-
If you squeeze the trigger of a gun really hard and really fast, it doesn't fire any faster or harder than if you just squeezed it gently.
快速有力地扣动扳机,并不比你轻扣扳机,射出的更加快速或更加有力
-
One should do," he says, "what archers do when attempting to reach a distant target, namely, aim your bow high, knowing that the force of gravity " will bring the arrow down."
他说：，“一个人应该做的是，模仿伟人所为,当试图达致遥不可及的目标时，意即将目标设高，明了重力会将,射出的箭吸回地面“
-
I tell you the initial velocity v0, I tell you at what angle I fire it.
我会告诉你们初速度 v0,以及我以多大角度射出
-
We have a zinc plate up here, and we're going to -- in a minute I'll describe how we can probe if electrons are coming off of it.
我们有一块向上的锌板，我们将在一分钟内描述,我们是怎样探测出,是否有电子从上面射出的。
-
So, we would expect to see electrons ejected with the UV light source.
所以，我们能够预测,可以看到电子被紫外光源射出。
-
So if we think about the work function for zinc, and the work function for zinc is 6.9 times 10 to the -19 joules, do we expect that when we shine our UV light on the zinc, we'll be able to eject electrons?
如果我们考虑锌的功函数,它是6，9乘以10的-19次方焦耳，我们是否可以预测当,用紫外灯照射锌时，我们可以射出电子呢？
-
So we can figure out the energy of each photon emitted by our UV lamp by saying e is equal to h c over wavelength.
所以我们可以计算出,每个从紫外光源射出的光子,也就是e等于h乘以c除以波长。
-
Also, what's the energy per photon of this red laser pointer, and then it's also worth trying a calculation dealing with intensity. So let's also try calculating the numbers of photons that would be emitted by this laser pointer, if, for example, we were to use it for 60 seconds and this were a one milliwatt laser.
同样，红色激光笔的,每个光子能量是多少，这也值得用处理强度的方法计算一下,让我们也计算一下,有多少光子会从这个激光笔射出，举个例子，如果我们使用它持续60秒,这里会有一毫瓦的激光。
应用推荐