谁能帮我做下大写物理题啊?1、在双缝干涉实验中,两缝间距为d,双缝与屏幕的距离为D (D>>d ),入射光波长为l,屏幕上相邻明条纹之间的距离为2、在玻璃(折射率为1.60)表面镀一层MgF2(折射率
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谁能帮我做下大写物理题啊?1、在双缝干涉实验中,两缝间距为d,双缝与屏幕的距离为D (D>>d ),入射光波长为l,屏幕上相邻明条纹之间的距离为2、在玻璃(折射率为1.60)表面镀一层MgF2(折射率
谁能帮我做下大写物理题啊?
1、在双缝干涉实验中,两缝间距为d,双缝与屏幕的距离为D (D>>d ),入射光波长为l,屏幕上相邻明条纹之间的距离为
2、在玻璃(折射率为1.60)表面镀一层MgF2(折射率为1.38)薄膜作为增透膜.为了使波长为500nm的光从空气(折射率为1.00)正入射时尽可能少反射,MgF2薄膜的最小厚度应是
(A) 125nm (B) 181nm (C) 250nm (D) 78.1nm (E) 90.6nm 3、在迈克尔逊干涉仪的一支光路中,放入一片折射率为n的透明介质薄膜后,测出两束光的光程差的改变量为一个波长l,则薄膜的厚度是
4、在光栅光谱中,假如所有偶数级次的主极大都恰好在单缝衍射的暗纹方向上,因而实际上不出现,那么此光栅每个透光缝宽度a和相邻两缝间不透光部分宽度b的关系为
5、一束光强为I0的自然光垂直穿过两个偏振片,此两偏振片的偏振化方向成45°角,若不考虑偏振片的反射和吸收,则穿过这两个偏振片后的光强I为
6、一束光强为I0的自然光,相继通过三个偏振片P1、P2、P3后,出射光的光强为 ,已知P1和P3的偏振化方向相互垂直,若以入射光线为轴,旋转P2最少要转过多大角度,才能使出射光的光强为零.
(A) 30° (B) 45° (C) 60° (D) 90°
7、单色光照射金属产生光电效应.已知金属表面的势垒是U0,则这种单色光的波长 一定满足的条件是:
二、填空题
1、在夫琅和费单缝衍射实验中,,表明在条纹对应衍射角 的方向上,单缝处的波阵面被分成___________个半波带,此时在位于透镜焦平面的屏上将形成_______________纹(明、暗).如果透镜焦距为f,则条纹在透镜焦平面屏上的位置x = ______________________.
2、在夫琅和费单缝衍射试验中,设第一级暗纹的衍射角很小,若钠黄光 中央明纹宽度为4.0mm,则 的篮紫色光的中央明纹宽度为 .
3、波长为500nm的单色光垂直入射到光栅常数为 的平面衍射光栅上,第一级衍射主极大所对应的衍射角 .
4、用每毫米有425条刻痕的平面光栅观察 的钠光谱,垂直入射时,能看到的最高级次谱线是第 级.若以 斜入射时,能看到的最高级次谱线是第 级,原来的零级谱线处现在是第 级.
5、一束光垂直入射在偏振片P上,以入射光线为轴转动P,观察通过P的光强的变化过程.若入射光是 ,则将看到光强不变;若入射光是 ,则将看到明暗交替变化,有时出现全暗;若入射光是 ,则将看到明暗交替变化,但不出现全暗.6、光子的波长为λ,则其能力E= ,动量的大小p= ,质量m = .
三、计算题:
1、用一束白光作为双缝干涉实验中的光源,已知两缝间距为0.25 mm,屏幕与双缝距离为1.50m,问在屏上观察到的第2级的彩色带宽有多宽?(可见光范围400~760nm)
2、在夫朗和费单缝衍射实验中,用单色光垂直照射单缝.已知入射光的波长为500纳米,第一级暗纹对应的衍射角为30°,试求:
(1)缝宽是多少?
(2)若单缝的宽度a = 0.5 mm,在焦距等于1米的凸透镜焦平面上观察衍射条纹,则中央明条纹以及第一级明条纹的宽度各是多少?
谁能帮我做下大写物理题啊?1、在双缝干涉实验中,两缝间距为d,双缝与屏幕的距离为D (D>>d ),入射光波长为l,屏幕上相邻明条纹之间的距离为2、在玻璃(折射率为1.60)表面镀一层MgF2(折射率
Ⅰ. Multiple choices (there is one correct answer only):
1. The center of mass a system of particles has a constant velocity if:
A. the forces exerted by the particles on each other sum to zero.
B. the external forces acting on particles of the system sum to zero.
C. the velocity of the center of mass is initially zero.
D. the particles are distributed symmetrically around the center of mass.
E. the center of mass is at the geometric center of the system
.
2. A wheel starts from rest and has an angular acceleration that is given by α(t)=6t2, where t is in seconds and α is in radians per second-squared. The time it takes to make 10 rev(转) is:
A. 2.8s
B. 3.3s
C. 4.0s
D. 4.7s
E. 5.3s
3. A spool(线轴) of wire rests on a horizontal surface as in Figure. As the wire is pulled, the spool does not slip at the contact point P. On separate trials, each one of the forces F1, F2, F3, and F4 is applied to the spool. Among these 4 forces, which one can make the spool roll in clockwise? (Note that the line of action of F2 passes through P.)
A. F1
B. F2
C. F3
D. F4
E. none of the above
4. A pulley with radius R and rotational inertia I is free to rotate on a horizontal fixed axis through its center. A string passes over the pulley. Mass m1 is attached to one end and mass m2 is attached to the other. At one time m1 is moving downward with speed v. If the string does not slip on the pulley, the magnitude of the total angular momentum, about the pulley center, of the masses and pulley, considered as a system, is given by:
A. (m1- m2)vR+Iv/R
B. (m1+ m2)vR+Iv/R
C. (m1- m2)vR-Iv/R
D. (m1+ m2)vR-Iv/R
E. none of the above
5. An ideal spring, with a pointer attached to its end, hangs next to a scale. With a 100-N weight attached and at rest, the pointer indicates “40” on the scale as shown. Using a 200-N weight instead results in “60” on the scale. Using an unknown weight X instead results in “30” on the scale. The weight of X is:
A. 10N
B. 20N
C. 30N
D. 40N
E. 50N
6. The potential energy for a body of mass m that is acted on by a very massive body is given by U=-mgx+kx2/2. The corresponding force is:
A. –mgx2/2+kx3/6.
B. mgx2/2-kx3/6.
C. –mg+kx/2
D. –mg+kx
E. mg-kx
7. Two particles, each of mass m, are a distance d apart. To bring a third particle, also with mass m, from far away to the point midway between the two particles an external force does work given by:
A. 4Gm2/d
B. -4Gm2/d
C. 4Gm2/d2
D. -4Gm2/d2
E. none of above
8. The displacement of a string carrying a traveling sinusoidal wave is given by y(x,t)=ymsin(kx-ωt-φ). At time t=0, the point at x=0 has a velocity of zero and a positive displacement. The phase constant φ is:
A. 45°
B. 90°
C. 135°
D. 180°
E. 270°
9. Two sinusoidal waves travel in the same direction and have the same frequency. Their amplitudes are y1m and y2m. The smallest possible amplitude of the resultant wave is:
A. y1m+ y2m and occurs when they are 180°out of phase
B. │y1m- y2m│and occurs when they are 180°out of phase
C. y1m+ y2m and occurs when they are in phase
D. │y1m- y2m│and occurs when they are in phase
E. │y1m- y2m│and occurs when they are 90°out of phase
10. Two sources, S1 and S2, each emit waves of wavelength λ in the same medium. The phase difference between the two waves, at the point P shown, is (2π/λ)(r2-r1)+φ. The quantity φ is:
A. the distance S1S2
B. the angle S1PS2
C. π/2
D. the phase difference between the two sources
E. zero for transverse waves, π for longitudinal waves
Ⅱ.Calculation problems (present the necessary equations in solution):
1、A bullet of mass m moving with velocity strikes and becomes embedded at the edge of a cylinder of mass M and radius R0, as shown in Fig. The cylinder, initially at rest, begins to rotate about its symmetry axis, which remains fixed in position. Assuming no frictional torque, what is the angular velocity of the cylinder after this collision? Is kinetic energy conserved?
2、As shown in Fig., a simple harmonic wave is traveling along the positive direction of X axis, the reflected point P is a node and and . Find: (1) the oscillation equation at position P caused by incidence wave; (2) the reflected wave equation; (3) the standing wave equation; (4) the resultant oscillation equation at position D.
3、How much work must be done to increase the speed of a particle with rest mass from rest to ( where is the speed of light in vacuum)?
4、 An observer A is at rest in the frame OXY while another observer B moves along the X-axis with a constant velocity 0.8c (c is the light speed in vacuum). In frame OXY the observer A find that the area enclosed by a geometric circle is 12 cm2. Relying on the relativistic effect of length contraction, this geometric figure becomes an ellipse for Observer B. What area is the ellipse enclosed measured by B? (It is known that the area of an ellipse with semimajor axis a (长半轴)and semiminor axis b (短半轴)can be calculated by Sab).
5、Figure shows a hypothetical speed distribution of N molecules in an ideal gas, with for and for . Find
(1) an expression for C in terms of N and ?
(2) the average speed of the particles:
(3) the rms speed of the particles?
6、A power plant generates 640 MW of electric power. It has an efficiency of 38% . At what rate does it dissipate heat? If a river carries the waste heat away, and environmental concerns limit the temperature rise of the water to 3oC, what mass flow rate(流量) is required in the river? (the specific heat capacity of water c=4200J/kgK)
7、One mole of a monatomic ideal gas initially at , is heated and expands at constant pressure to a volume 4V0. It is then cooled at constant volume until the pressure has dropped to 0.5 . Calculate (a) the work done: (b) the change in internal energy, (c) the heat flow, and (d) the net change in entropy.
8、An ideal(Carnot) engine operates between a hot reservoir at 360K and a cold reservoir at 270K. It absorbs 600J of heat per cycle at the hot reservoir. (a) How much work does it do each cycle? (b) If the same engine is operated in reverse as a refrigerator, how much work must be done each cycle in order to remove 1200J of heat from the cold reservoir each cycle? (c) An engine manufacturer makes the following claims: The heat input per cycle of the engine is 600J at 360K. The heat output per cycle is 420J at 270K. Do you believe these claims? Why?
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