弗兰克赫兹实验报告

1、弗兰克-赫兹实验报告【实验数据及处理】1、 Hg管表1 参数U1U3温度1.5V2.0V176表2 粗测峰（n）1234567Ukg2/V1.14.99.714.519.524.429.3表3 Hg管扫描电压Ukg2与Uout记录表Ukg2/VUout/VUkg2/VUout/VUkg2/VUout/V0.00.0055.00.0329.90.1460.20.0065.10.03010.00.1300.40.0075.20.02910.10.1090.70.0075.30.02710.30.0771.00.0065.40.02210.50.0441.10.0075.50.01710.70.03

2、41.20.0065.80.01311.00.0201.40.0066.00.00911.20.0141.50.0066.20.00711.40.0131.80.0076.40.00711.60.0162.00.0076.60.00811.90.0232.20.0076.80.00912.20.0362.50.0077.00.01012.50.0612.70.0077.20.01212.80.0822.90.0077.50.01913.10.1153.20.0097.80.02513.40.1583.40.0108.20.04413.60.2063.70.0128.40.05413.80.24

3、44.00.0148.60.07114.00.2824.10.0168.80.09314.20.3234.20.0189.10.11814.30.3404.30.0199.20.12614.50.3444.40.0209.30.13814.60.3394.50.0239.40.14314.80.2764.60.0269.50.15315.00.2154.70.0279.60.15815.30.1344.80.0309.70.15815.50.0944.90.0319.80.15615.80.05116.00.04020.50.11525.60.21416.20.02820.80.07425.9

4、0.12516.30.02620.90.06726.10.11016.40.02521.10.04426.30.09416.50.02921.30.04526.40.09416.70.03421.50.05026.50.09716.90.04721.80.07026.80.11517.20.07522.10.10427.20.16917.50.11622.50.16527.50.24517.80.17022.80.24027.80.32818.10.22423.10.30828.10.42218.40.30823.40.40928.40.52818.60.34723.60.49728.60.6

5、4018.80.39823.80.58328.90.76419.00.46224.00.62329.00.80219.20.49524.20.66929.10.79519.30.50424.30.67129.20.79119.40.47224.40.65929.40.75719.50.43924.50.62529.70.69919.60.40524.80.52630.00.53719.90.29825.00.46420.20.21025.30.317表4 Hg管峰值表n1234567Ukg2/V1.15.09.614.519.324.329.0线性拟合后，得直线，相关系数,标准差V2、 减速电

6、压U3对实验的影响（使用Hg管）表5 参数U1U3温度1.5V3.5V176表6 改变U3后的Ukg2与Uout记录表Ukg2/VUout/VUkg2/VUout/VUkg2/VUout/V23.40.07425.60.08228.70.16123.60.11225.90.05828.90.18323.80.14826.20.03929.00.19524.00.16726.50.02929.10.21524.20.20426.90.02029.20.22624.30.21627.10.01829.30.23824.40.22527.30.01929.50.24524.50.22027.60.0

7、2729.70.24224.70.20328.00.05229.90.22125.00.16228.40.09630.00.20925.30.13128.60.1393、 Ar管表7 Ar管扫描电压Ukg2与Uout记录表Ukg2/VUout/VUkg2/VUout/VUkg2/VUout/V9.60.134.73.36089.90.1353.460.48.610.40.235.43.860.89.210.70.235.84.161.29.7110.336.24.661.61011.30.536.65.16210.511.70.6375.762.410.912.10.937.46.262.81

8、1.212.51.337.86.763.211.512.91.838.27.263.511.613.32.138.67.663.911.713.62.239864.111.8142.539.38.264.411.814.42.839.68.364.811.814.83.1408.665.111.715.23.240.38.765.311.615.63.440.68.765.711.5163.540.98.766.111.116.43.641.28.766.510.716.83.741.48.666.910.217.23.841.88.467.39.717.43.642.28.167.79.21

9、7.63.642.67.768.18.517.83.5437.268.57.918.13.543.46.668.97.518.53.543.8669.37.318.93.544.25.469.77.119.33.444.64.770.17.219.73.4454.270.57.420.13.445.4470.97.720.43.345.8471.38.220.83.246.24.171.78.721.23.146.64.472.19.221.63474.872.59.7222.847.45.472.910.222.42.747.86.173.310.622.82.648.26.873.711.

10、123.22.548.67.374.111.423.62.5497.974.511.8242.749.38.474.912.324.32.849.78.875.212.524.73.1509.275.612.7253.350.39.575.812.925.43.650.79.876.212.925.73.9511076.313264.151.11076.513.126.44.551.310.176.913.226.74.851.410.177.213.2275.151.610.277.413.227.35.451.810.377.613.127.75.752.110.4781328.1652.

11、410.478.412.828.46.252.710.478.812.428.76.35310.379.212.1296.553.410.279.611.729.36.553.89.98011.229.76.554.29.580.410.7306.454.69.180.810.330.36.3558.581.21030.56.255.47.881.69.730.8655.87.1829.631.15.856.26.582.49.531.55.556.65.882.89.731.85.2575.583.29.932.24.857.45.383.610.132.64.457.85.38410.43

12、34585.584.410.833.43.658.45.984.811.333.83.358.86.38511.434.23.259.26.734.63.259.67.4表8 Ar管峰值表n123456Ukg2/V17.229.440.952.764.477.2线性拟合得直线，相关系数标准差【思考题】改变减速电压Ug2p对曲线有何影响？并用实验验证。实验发现，在不同的Ug2p下，Ukg2-Uout的图线走势相同，但有一个整体的移动。当Ug2p增加时，图线向右下方移动。图中仅画出Hg管的最后两个峰。【分析】当反向电压Ug2p增大时会有更多的电子在到达p极板之前损失掉所有的动能，不能形成电流。因此

13、，仅就图线的峰来说，它对应着电子在到达栅极g2时，绝大多数动能刚好略小于原子的激发能，增加Ug2p会使得峰的高度降低。同时，为了使得到达极板p的电子数占总数的比重最大，在提高Ug2p的同时，也要提高Ukg2的大小。这是因为提高Ukg2会让电子到达栅极g2时的动能加大，更多比重的电子会跨过Ug2p的阻碍到达极板p，形成电流，所以峰也要向右移动。综合两个方面分析，当Ug2p增加时，图像会向右下方移动。【分析与讨论】1. 实验中测得的各种曲线有什么主要特征？如何理解？有明显的周期性。随着Ukg2的增大，Uout的峰值和谷值均逐渐增大，各峰值之间有明显的线性关系。1 周期性。电流的周期性来源于电子与气

14、体原子间的碰撞。电压从零开始增加时，电子动能也随之增加，射向阳极的电子数也增加，这时虽然电子与汞原子间有碰撞，但这时属于弹性碰撞，电子并不损失能量因而电流随电压增加而增加。当电压超过U1时，电子与汞原子发生非弹性碰撞，使汞原子从基态跃迁到激发态，电子因损失了动能而不能克服反向电压Ugp的阻滞到达极板p，从而电流下降。电压继续增加，发生非弹性碰撞后的电子动能继续增加，当电子的动能大于|eUgp|时，它就能到达极板p，从而使电流上升。当电压超过2U1时，电子与汞原子又发生非弹性碰撞，电流再次下降，多次重复，就形成了具有明显周期性的特性曲线。2 峰点连线。实验结果表明，峰点的连线是一条直线，该直线既

15、不依赖于灯丝电压的变化，也不依赖于Ug2p的变化，应该是弗兰克赫兹管某种固有性质的表现。考虑到该直线的斜率具有电导的量纲，所以，该直线斜率代表的是弗兰克赫兹管的临界电导（即临界状态下的电导）1。3 谷底高度。极板电流与加速电压关系曲线的谷底不在横坐标轴上，而具有一定的高度。这一特征表明，即使是在热电子与气体原子发生碰撞损失能量的高峰期，极板电流也不为0。此时，极板电流由那些没有因碰撞而损失能量的热电子的贡献所致，称之为谷底电流（反映的是不因碰撞而损失能量的热电子的概率）。谷底电流有以下特点：1）第一个谷底为电子不发生一次碰撞的概率，第二个谷底为电子不发生一次碰撞的概率与发生一次碰撞的但不发生第二次碰撞的概率之和，以此类推；2）前三个谷底均较为偏低，反应出热电子在与气体原子发生碰撞损失能量的过程中，发生13次连续碰撞的概率