^rAGNETO-OPTTC PHEN'OMRNA OP TRON, NICKEL, AND COBALT. 
no 
A = 
B = 
A 
OJ 
From these expressions we see that, if the incident ray is polarised in the plane 
of incidence, so that Aq = 0 , the expression for the reflected ray does not involve ; 
and so the magnetisation produces no effect. This is in agreement with the 
prediction of Wind. 
But if the incident ray be polarised perpendicularly to the plane of incidence, so 
that B(, = 0, the reflected ray is given by A, which does contain 17,^. Instead of 
having 
. _ — (RV‘® — M/wi) 
^ ~ ' (R-V‘“ + M/m) 
as would be the case if there were no magnetisation, we have A equal to this value 
multiplied by the factor 
1 + (Ijm) CoC‘*''/3o}/{PA2‘“ + ’ 
which is the same as 
1 -f- 2eX.sin 2i. 
L.e ‘ 
RV*® (cos i — (cos I -f JlflR ’ 
and the effect of this factor, which of course differs from unity by only a very small 
quantity, is to slightly alter both the amplitude and the phase of the still plane- 
polarised reflected ray. 
Now the change of phase produced by a factor of the form 1 + Qe'^g where Q is 
very small, is tan“^ {Q sin (j/(l + Q cos cy)}, and therefore, in circular measure, 
is approximately Q sin q. 
Hence, if for brevity we put 
cos i — = Ye‘b cos i -f- 
the acceleration of phase produced in the reflected ray by the component of 
magnetisation is, in circular measure. 
Cq.j8q.2c\. 
sin 2'i 
R‘. Y . Y 
7 sin (x -j- 90° — y — y — 4a). 
In Zeeman’s experiment the angle of incidence was 75° and the intensity of 
