弗蘭克赫茲實(shí)驗(yàn)報(bào)告(一)

1、13/13弗蘭克-赫茲實(shí)驗(yàn)報(bào)告實(shí)驗(yàn)數(shù)據(jù)與處理Hg管表1 參數(shù)U1U3溫度1.5V2.0V176表2 粗測(cè)峰（n）1234567Ukg2/V1.14.99.714.519.524.429.3表3 Hg管掃描電壓Ukg2與Uout記錄表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線性擬合后，得直線，相關(guān)系數(shù),標(biāo)準(zhǔn)差V減速電壓U3

6、對(duì)實(shí)驗(yàn)的影響（使用Hg管）表5 參數(shù)U1U3溫度1.5V3.5V176表6 改變U3后的Ukg2與Uout記錄表Ukg2/VUout/VUkg2/VUout/VUkg2/VUout/V23.40.07425.60.08228.70.16123.60.11225.90.05828.90.18323.80.14826.20.03929.00.19524.00.16726.50.02929.10.21524.20.20426.90.02029.20.22624.30.21627.10.01829.30.23824.40.22527.30.01929.50.24524.50.22027.60.0272

7、9.70.24224.70.20328.00.05229.90.22125.00.16228.40.09630.00.20925.30.13128.60.139Ar管表7 Ar管掃描電壓Ukg2與Uout記錄表Ukg2/VUout/VUkg2/VUout/VUkg2/VUout/V9.60.134.73.36089.90.1353.460.48.610.40.235.43.860.89.210.70.235.84.161.29.7110.336.24.661.61011.30.536.65.16210.511.70.6375.762.410.912.10.937.46.262.811.212.

8、51.337.86.763.211.512.91.838.27.263.511.613.32.138.67.663.911.713.62.239864.111.8142.539.38.264.411.814.42.839.68.364.811.814.83.1408.665.111.715.23.240.38.765.311.615.63.440.68.765.711.5163.540.98.766.111.116.43.641.28.766.510.716.83.741.48.666.910.217.23.841.88.467.39.717.43.642.28.167.79.217.63.6

9、42.67.768.18.517.83.5437.268.57.918.13.543.46.668.97.518.53.543.8669.37.318.93.544.25.469.77.119.33.444.64.770.17.219.73.4454.270.57.420.13.445.4470.97.720.43.345.8471.38.220.83.246.24.171.78.721.23.146.64.472.19.221.63474.872.59.7222.847.45.472.910.222.42.747.86.173.310.622.82.648.26.873.711.123.22

10、.548.67.374.111.423.62.5497.974.511.8242.749.38.474.912.324.32.849.78.875.212.524.73.1509.275.612.7253.350.39.575.812.925.43.650.79.876.212.925.73.9511076.313264.151.11076.513.126.44.551.310.176.913.226.74.851.410.177.213.2275.151.610.277.413.227.35.451.810.377.613.127.75.752.110.4781328.1652.410.47

11、8.412.828.46.252.710.478.812.428.76.35310.379.212.1296.553.410.279.611.729.36.553.89.98011.229.76.554.29.580.410.7306.454.69.180.810.330.36.3558.581.21030.56.255.47.881.69.730.8655.87.1829.631.15.856.26.582.49.531.55.556.65.882.89.731.85.2575.583.29.932.24.857.45.383.610.132.64.457.85.38410.4334585.

12、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線性擬合得直線，相關(guān)系數(shù)標(biāo)準(zhǔn)差思考題改變減速電壓Ug2p對(duì)曲線有何影響？并用實(shí)驗(yàn)驗(yàn)證。實(shí)驗(yàn)發(fā)現(xiàn)，在不同的Ug2p下，Ukg2-Uout的圖線走勢(shì)一樣，但有一個(gè)整體的移動(dòng)。當(dāng)Ug2p增加時(shí)，圖線向右下方移動(dòng)。圖中僅畫出Hg管的最后兩個(gè)峰。分析當(dāng)反向電壓Ug2p增大時(shí)會(huì)有更多的電子在到達(dá)p極板之前損失掉所有的動(dòng)能，不能形成電流。因此，僅就圖線的峰來(lái)說(shuō)，

13、它對(duì)應(yīng)著電子在到達(dá)柵極g2時(shí)，絕大多數(shù)動(dòng)能剛好略小于原子的激發(fā)能，增加Ug2p會(huì)使得峰的高度降低。同時(shí)，為了使得到達(dá)極板p的電子數(shù)占總數(shù)的比重最大，在提高Ug2p的同時(shí)，也要提高Ukg2的大小。這是因?yàn)樘岣遀kg2會(huì)讓電子到達(dá)柵極g2時(shí)的動(dòng)能加大，更多比重的電子會(huì)跨過(guò)Ug2p的阻礙到達(dá)極板p，形成電流，所以峰也要向右移動(dòng)。綜合兩個(gè)方面分析，當(dāng)Ug2p增加時(shí)，圖像會(huì)向右下方移動(dòng)。分析與討論實(shí)驗(yàn)中測(cè)得的各種曲線有什么主要特征？如何理解？有明顯的周期性。隨著Ukg2的增大，Uout的峰值和谷值均逐漸增大，各峰值之間有明顯的線性關(guān)系。周期性。電流的周期性來(lái)源于電子與氣體原子間的碰撞。電壓從零開始增加時(shí)

14、，電子動(dòng)能也隨之增加，射向陽(yáng)極的電子數(shù)也增加，這時(shí)雖然電子與汞原子間有碰撞，但這時(shí)屬于彈性碰撞，電子并不損失能量因而電流隨電壓增加而增加。當(dāng)電壓超過(guò)U1時(shí)，電子與汞原子發(fā)生非彈性碰撞，使汞原子從基態(tài)躍遷到激發(fā)態(tài)，電子因損失了動(dòng)能而不能克服反向電壓Ugp的阻滯到達(dá)極板p，從而電流下降。電壓繼續(xù)增加，發(fā)生非彈性碰撞后的電子動(dòng)能繼續(xù)增加，當(dāng)電子的動(dòng)能大于|eUgp|時(shí)，它就能到達(dá)極板p，從而使電流上升。當(dāng)電壓超過(guò)2U1時(shí)，電子與汞原子又發(fā)生非彈性碰撞，電流再次下降，多次重復(fù)，就形成了具有明顯周期性的特性曲線。峰點(diǎn)連線。實(shí)驗(yàn)結(jié)果表明，峰點(diǎn)的連線是一條直線，該直線既不依賴于燈絲電壓的變化，也不依賴于Ug

15、2p的變化，應(yīng)該是弗蘭克赫茲管某種固有性質(zhì)的表現(xiàn)?？紤]到該直線的斜率具有電導(dǎo)的量綱，所以，該直線斜率代表的是弗蘭克赫茲管的臨界電導(dǎo)（即臨界狀態(tài)下的電導(dǎo)）1。谷底高度。極板電流與加速電壓關(guān)系曲線的谷底不在橫坐標(biāo)軸上，而具有一定的高度。這一特征表明，即使是在熱電子與氣體原子發(fā)生碰撞損失能量的高峰期，極板電流也不為0。此時(shí)，極板電流由那些沒(méi)有因碰撞而損失能量的熱電子的貢獻(xiàn)所致，稱之為谷底電流（反映的是不因碰撞而損失能量的熱電子的概率）。谷底電流有以下特點(diǎn)：1）第一個(gè)谷底為電子不發(fā)生一次碰撞的概率，第二個(gè)谷底為電子不發(fā)生一次碰撞的概率與發(fā)生一次碰撞的但不發(fā)生第二次碰撞的概率之和，以此類推；2）前三個(gè)谷底均較為偏低，反應(yīng)出熱電子在與氣體原子發(fā)生碰撞損失能量的過(guò)程中，發(fā)