Question

matlab画函数曲线

这个是物理课的一个作业，题目本身很好理解也很简单，但是我从来没用过matlab，一点都不会，求指导：
题目：

The ultravioletcatastrophe, was a prediction of late 19th century/early 20th century classicalphysics that an ideal black body at thermal equilibrium will emit radiationwith infinite power. It can be directly seen from the so called theRayleigh–Jeans law

where (B𝜆(T) is energy emitted per unit time per unit area ofemitting surface, per unit solid angle, per unit wavelength, c is a speed oflight, k is Boltzmann constant and T is a temperature of the black body).

In 1900 Max Planckempirically obtained an expression for black-body radiation expressed in termsof wavelength

where (h – is Planck’s constant).
The Planck law did not suffer from an ultraviolet catastrophe,agreed well with the experimental data, and eventually led to the quantum theory.
Use Matlab to plot in the same graph Rayleigh–Jeans lawvs Planck’s black body formula for
a) T1=1000 K,
b) T2=6000 K.
c) Plot an integral of Plank’s formula over all spectrum for the temperature range T from0 to 6000K.
就是说要在同一个图上面画出上面两个函数：
a）T=1000的时候，
b）T=6000的时候，
c）积分那个函数式

（c是光速，h是普朗克常数，k是玻尔兹曼常数）





Answer 1

c = 3.00e8;

h = 6.63e-34;

k = 1.38e-23;

lambda = (1:10:5000).*1e-9;

figure(1)

subplot(2,1,1);

T=1000;

B1 = 2*h*c^2 ./ (lambda.^5 .* (exp( h*c/(k*T)./lambda)-1));

plot(lambda,B1,'r');

title('T=1000K');

subplot(2,1,2);

T = 6000;

B2 = 2*h*c^2 ./ (lambda.^5 .* (exp( h*c/(k*T)./lambda)-1));

plot(lambda,B2,'b');

title('T=6000K');

最后一题 c) 因为对这个式子积分不太会（应该可以用数值积分），积分范围从-∞开始吗？λ为负没有意义吧。

Answer 2

我英文不太好，中文解释哈，我说不定能搞定！