This article is a memo after study, the level is limited, if there is an error, please understand.
The parameters without ' are the parameters of the static reference frame X, and the parameters with ' are the parameters of the moving reference frame X'.
1. Lorentz transformation
令k = 1 − u 2 / c 2 k=\sqrt{1-u^2/c^2}k=1−u2/c2
x ′ = x − u t k x'=\frac{x-ut}{k} x′=kx−ut
y′ = y y'=yy′=y
z ′ = z z'=z z′=z
t ′ = t − u x / c 2 k t'=\frac{t-ux/c^2}{k} t′=kt−ux/c2
2. Speed change
v x ′ = d x ′ d t ′ = d x − u d t d t − u c 2 d x = v x − u 1 − u c 2 v x v'_x=\frac{dx'}{dt'}=\frac{dx-udt}{dt-\frac{u}{c^2}dx}=\frac{v_x-u}{1-\frac{u}{c^2}v_x} vx′=dt′dx′=dt−c2udxdx−u d t=1−c2uvxvx−u
v y ′ = d y ′ d t ′ = k d y d t − u c 2 d x = k v y 1 − u c 2 v x v'_y=\frac{dy'}{dt'}=k\frac{dy}{dt-\frac{u}{c^2}dx}=k\frac{v_y}{1-\frac{u}{c^2}v_x} vy′=dt′dy′=kdt−c2udxdy=k1−c2uvxvy
v z ′ = d z ′ d t ′ = k d z d t − u c 2 d x = k v z 1 − u c 2 v x v'_z=\frac{dz'}{dt'}=k\frac{dz}{dt-\frac{u}{c^2}dx}=k\frac{v_z}{1-\frac{u}{c^2}v_x} vz′=dt′dz′=kdt−c2udxdz=k1−c2uvxvz
Transformation of three momentums
由 m ′ = m 0 1 − v ′ 2 c 2 m'=\frac{m_0}{\sqrt{1-\frac{v'^2}{c^2}}} m′=1−c2v′2m0和 m = m 0 1 − v 2 c 2 m=\frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}} m=1−c2v2m0得m ′ = m 1 − v 2 c 2 1 − v ′ 2 c 2 m'=m\frac{\sqrt{1-\frac{v^2}{c^2}}}{\sqrt{1- \frac{v'^2}{c^2}}}m′=m1−c2v′21−c2v2
Now to v ′ v'v′ andvx ′ v'_xvx′用K系电影电影电影。
v ′ 2 = vx ′ 2 + vy ′ 2 + vz ′ 2 = ( vx − u ) 2 + ( kvy ) 2 + ( kvz ) 2 ( 1 − uc 2 vx ) 2 v'^2 =v'^2_x+v'^2_y+v'^2_z=\frac{(v_x-u)^2+(kv_y)^2+(kv_z)^2}{(1-\frac{u}{c ^2}v_x)^2}v′2=vx′2+vy′2+vz′2=(1−c2uvx)2(vx−u)2+(kvy)2+(kvz)2
化简得1 − v ′ 2 c 2 = k 1 − v 2 c 2 1 − uc 2 vx \sqrt{1-\frac{v'^2}{c^2}}=\frac{k\sqrt{ 1-\frac{v^2}{c_2}}}{1-\frac{u}{c^2}v_x}1−c2v′2=1−c2uvxk1−c2v2
因此 P x ′ = m ′ v x ′ = m k ( 1 − u c 2 v x ) v x ′ = m k ( v x − u ) = P x − u c 2 E k P'_x=m'v'_x=\frac{m}{k}(1-\frac{u}{c^2}v_x)v'_x=\frac{m}{k}(v_x-u)=\frac{P_x-\frac{u}{c^2}E}{k} Px′=m′vx′=km(1−c2uvx)vx′=km(vx−u)=kPx−c2uE
Py ′ = Py P'_y=P_yPy′=Py
P z ′ = P z P'_z=P_z Pz′=Pz
4. Transformation of force
fx ′ = d P x ′ dt ′ = (need to change K ′ variable into K variable, after simplification) = fx − ufyvyc 2 ( 1 − uc 2 vx ) − ufzvzc 2 ( 1 − uc 2 vx ) f '_x=\frac{dP'_x}{dt'}=(Need to change K' variable into K variable, after simplification)=f_x-\frac{uf_yv_y}{c^2(1-\frac{ u}{c^2}v_x)}-\frac{uf_zv_z}{c^2(1-\frac{u}{c^2}v_x)}fx′=dt′dPx′=( Need to put K' variable becomesKvariable, after simplification)=fx−c2(1−c2uvx)ufyvy−c2(1−c2uvx)ufzvz
fy ′ = (need to change K ′ variable into K variable, after simplification) = kfy 1 − uc 2 vx f'_y=(need to change K' variable into K variable, after simplification)=\ frac{kf_y}{1-\frac{u}{c^2}v_x}fy′=( Need to put K' variable becomesKvariable, after simplification)=1−c2uvxkfy
fz ′ = (Need to change K ′ variable into K variable, after simplification) = kfz 1 − uc 2 vx f'_z=(Need to change K' variable into K variable, after simplification)=\ frac{kf_z}{1-\frac{u}{c^2}v_x}fz′=( Need to put K' variable becomesKvariable, after simplification)=1−c2uvxkfz
5. The source of the magnetic effect
In the above figure, for the convenience of calculation, it is assumed that the origins of the two coordinate systems coincide at this time. The K' system moves in the positive direction of the x-axis relative to the K system at the speed u. q 0 q_0q0At the origin, relative to the K system, q 1 q_1q1在 r ( r x , r y , r z ) r(r_x,r_y,r_z) r(rx,ry,rz) place. Relative to the K system at the speedv 1 ( ( v 1 ) x , ( v 1 ) y , ( v 1 ) z ) v_1((v_1)_x,(v_1)_y,(v_1)_z)v1((v1)x,(v1)y,(v1)z) movement.. Now examinethe stress situation of q 1 The stress situation of q_1q1的受力情况
f x ′ = f x − u f y v y c 2 ( 1 − u c 2 v x ) − u f z v z c 2 ( 1 − u c 2 v x ) f'_x=f_x-\frac{uf_yv_y}{c^2(1-\frac{u}{c^2}v_x)}-\frac{uf_zv_z}{c^2(1-\frac{u}{c^2}v_x)} fx′=fx−c2(1−c2uvx)ufyvy−c2(1−c2uvx)ufzvz
whereuc 2 fyvy = uc 2 E yq 1 vy = uc 2 q 0 4 π e 0 ry 2 q 1 vy \frac{u}{c^2}f_yv_y=\frac{u}{c^2}E_yq_1v_y=\ frac{u}{c^2}\frac{q_0}{4\pi e_0r^2_y}q_1v_yc2ufyvy=c2uEyq1vy=c2u4 pi e0ry2q0q1vy
Because 1 c 2 = μ 0 e 0 \frac{1}{c^2}=\mu_0 e_0c21=m0e0
Let uc 2 fyvy = q 1 vy ( μ 0 uq 0 4 π ry 2 ) \frac{u}{c^2}f_yv_y=q_1v_y(\frac{\mu_0uq_0}{4\pi r^2_y})c2ufyvy=q1vy(4πry2m0uq0)
同理, u c 2 f z v z = q 1 v z ( μ 0 u q 0 4 π r z 2 ) \frac{u}{c^2}f_zv_z=q_1v_z(\frac{\mu_0uq_0}{4\pi r^2_z}) c2ufzvz=q1vz(4πrz2m0uq0)
则fx ′ = fx − q 1 vy 1 − uc 2 vx ( q 0 μ 0 u 4 π ry 2 ) − q 1 vz 1 − uc 2 vx ( q 0 μ 0 u 4 π rz 2 ) = fx − q 1 vy ′ ( q 0 μ 0 u 4 π ry 2 k ) − q 1 vz ′ ( q 0 μ 0 u 4 π rz 2 k ) f'_x=f_x-q_1\frac{v_y}{1-\frac{ u}{c^2}v_x}(\frac{q_0\mu_0u}{4\pi r^2_y})-q_1\frac{v_z}{1-\frac{u}{c^2}v_x}(\ frac{q_0\mu_0u}{4\pi r^2_z})=f_x-q_1v'_y(\frac{q_0\mu_0u}{4\pi r^2_yk})-q_1v'_z(\frac{q_0\mu_0u} {4\pi r^2_zk})fx′=fx−q11−c2uvxvy(4πry2q0m0u)−q11−c2uvxvz(4πrz2q0m0u)=fx−q1vy′(4πry2kq0m0u)−q1vz′(4πrz2kq0m0u)
Same calculation,
fy ′ = fyk 1 − uc 2 vx = fyk ( 1 + uvx ′ c 2 ) = fyk + q 1 vx ′ q 0 μ 0 u 4 π ry 2 k f'_y=\frac{f_yk}{ 1-\frac{u}{c^2}v_x}=\frac{f_y}{k}(1+\frac{uv'_x}{c^2})=\frac{f_y}{k}+q_1v '_x\frac{q_0\mu _0u}{4\pi r^2_yk}fy′=1−c2uvxfyk=kfy(1+c2uvx′)=kfy+q1vx′4πry2kq0m0u
f z ′ = f z k 1 − u c 2 v x = f z k ( 1 + u v x ′ c 2 ) = f z k + q 1 v x ′ q 0 μ 0 u 4 π r z 2 k f'_z=\frac{f_zk}{1-\frac{u}{c^2}v_x}=\frac{f_z}{k}(1+\frac{uv'_x}{c^2})=\frac{f_z}{k}+q_1v'_x\frac{q_0\mu _0u}{4\pi r^2_zk} fz′=1−c2uvxfzk=kfz(1+c2uvx′)=kfz+q1vx′4πrz2kq0m0u
Note that the following three formulas are used here to replace the K-system speed with the K'-system speed vx ′ , vy ′ , vz ′ v'_x,v'_y,v'_zvx′,vy′,vz′。
v x = v x ′ + u 1 + u c 2 v x ′ v_x=\frac{v'_x+u}{1+\frac{u}{c^2}v'_x} vx=1+c2uvx′vx′+u
v y = k v y ′ 1 + u c 2 v x ′ v_y=k\frac{v'_y}{1+\frac{u}{c^2}v'_x} vy=k1+c2uvx′vy′
v z = k v z ′ 1 + u c 2 v x ′ v_z=k\frac{v'_z}{1+\frac{u}{c^2}v'_x} vz=k1+c2uvx′vz′
The above about fx ′ , fy ′ , fz ′ f'_x, f'_y, f'_zfx′,fy′,fz′The meaning of the three formulas is that when a charged particle q 0 q_0q0speed uuWhen u moves in the negative direction of the x-axis, the charged particle q 1 q_1moving at the speed v'q1at q0 q_0q0The force in the generated electric field is f ′ ( fx ′ , fy ′ , fz ′ ) f'(f'_x,f'_y,f'_z)f′(fx′,fy′,fz′) , each direction can be written asf + qv ′ B f+qv'Bf+qv′ Bform
whereB i = q 0 μ 0 u 4 π ri 2 k B_i=\frac{q_0 \mu_0 u}{4\pi r^2_ik}Bi=4πri2kq0m0u