大学物理小抄物理4

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1、专业好文档 光的强度：单位时间内通过与光传播方向垂直的单位面 积的光子束所具有的总能量 1、 导体的三种情况：1.价带是未填满的导带（电子易从低能级向高能级跃迁）2. 价带是满带，但满带与空带相重叠（电子易从满带跃迁至空带）3.价带是未满的导带，又与相邻的空带重合2、绝缘体：价带为满带，且满带与空带之间的禁带宽度较大，电子很难跃迁导电3、半导体：价带是满带，满带与空带之间的禁带宽度较小。电子容易从满带被激发到空带中去，从而电子和空穴都参与导电 4、本征半导体：不含任何杂质的半导体，导电率很低。导电机理：电子和空穴混合导电。本征载流子：电子和空穴5、N型半导体（电子型）：施主杂质：能向导带中提供

2、电子的杂质。施主能级处于禁带中，但接近导带底。6、P型半导体（空穴型）：受主能级处于禁带中，但接近满带顶7、自发辐射：处于高能级上的原子自发的向低能级跃迁而辐射出一个光子的过程8、受激辐射：在入射光的激励下（激光）受激辐射发出的光与入射光的频率、初相位、偏振态均相同受激吸收：在入射光的激励下向高能级跃迁的过程9、（1）自发辐射的光波是非相关的，受激辐射的光波是相关的（2）受激辐射和受激吸收与入射光的光强有关（3）在热平衡条件下，两能级受激吸收的概率大于受激辐射的概率10、产生激光的必要条件：介质中粒子数反转（高能级原子数超过低能级原子数）。11、实现粒子反转的条件：激励能源（提供能量）；激活物

3、质（有适当的能级结构：亚稳态）12、激励的方法：光激励、气体放电激励、化学反应激励、 核能激励等。13、光学谐振腔的作用：1.产生并维持光振荡，使光得到加强放大。2.提高激光的方向性。3.具有选频作用，提高激光的单色性14、激光的特征：1.高定向性；2.高单色性；3.高亮度；4.极好的相干性15、世界上第一台激光器是：红宝石激光器。16、激光全息照相技术主要利用激光的：相干性好 无限长直线 无限大平面 细圆环中轴线特别地（圆心处） 均匀带点球面球内 ： 球外： 长直螺线管 n：线圈密度一段直线电流螺绕环内 r到通电线圈环中心的距离无限大平面电流无限长载流圆柱导体:1.平面载流线圈的磁矩2.均匀

4、磁场中载流线圈所受的磁力矩3.磁场中任一点放一个小的载流试验线圈可以确定该点的磁感应强度，其大小等于放在该点处试验线圈所受的 最大磁力矩和线圈的 磁矩的比值4.磁化电流5.磁化电流的性质：6.软磁材料的特点是 磁导率大，矫顽力小 ，磁质损耗低 ，它们适于用来制造 变压器，交流电机的铁芯 等光的波粒二项性对于各项同性介质麦克斯韦方程组Winger Tuivasa-Sheck, who scored two tries in the Kiwis 20-18 semi-final win over England, has been passed fit after a lower-leg inju

5、ry, while Slater has been named at full-back but is still recovering from a knee injury aggravated against USA.Both sides boast 100% records heading into the encounter but Australia have not conceded a try since Josh Charnleys effort in their first pool match against England on the opening day.Aussi

6、e winger Jarryd Hayne is the competitions top try scorer with nine, closely followed by Tuivasa-Sheck with eight.But it is recently named Rugby League International Federation player of the year Sonny Bill Williams who has attracted the most interest in the tournament so far.The Kiwi - with a tourna

7、ment high 17 offloads - has the chance of becoming the first player to win the World Cup in both rugby league and rugby union after triumphing with the All Blacks in 2011.Id give every award back in a heartbeat just to get across the line this weekend, said Williams.The (lack of) air up there Watch

8、mCayman Islands-based Webb, the head of Fifas anti-racism taskforce, is in London for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport

9、.For me its about how he felt and I would like to speak to him first to find out what his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1 win.Michel Platini, president of European footballs governing body, has also ordered an

10、immediate investigation into the referees actions.CSKA said they were surprised and disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early

11、as Sunda.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the tropo

12、sphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the trop

13、opause),e can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.They blew it in 2008 when they got caught cold in the final and they will not make the same

14、 mistake against the Kiwis in Manchester.Five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by Englands Josh Charnley in the opening game of the tournament.That could be classed as a weakness, a team under-cooked - but

15、 I have been impressed by the Kangaroos focus in their games since then.They have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. Theyve been great at all the unglamorous stuff that

16、 often goes unnoticed in the stands but not by your team-mates.It is as though their entire tournament has been preparation for the final.In Johnathan Thurston, Cooper Cronk, Cameron Smith and either Billy Slater or Greg Inglis at full-back they have a spine that is unmatched in rugby league. They h

17、ave played in so many high-pressure games - a priceless asset going into Saturday.The Kiwis are a lot less experienced but winning a dramatic match like their semi-final against England will do wonders for their confidence.They defeated Australia in the Four Nations final in 2010 and the last World Cup, and know they can rise to the big occasion.