384 Mr Bevan, The Influence on Light reflected from and 
This equation gives for any direction of wave motion only one 
velocity, so that in whatever plane the light is polarised the 
velocity is the same and there is no difference of phase of the 
components of any vibration introduced on progression through 
the metal. 
For light incident normally 1 = 0 and the effects on re- 
flected and transmitted light are the same as when no current 
flows. 
Consider light, polarised in the plane of incidence, incident 
on the metal, the forces varying as e L(lx+my+nz+pt) . The values of 
l, m, n in equation (3) will be l, m and say v. 
The ratio of the amplitude of the reflected light to that of the 
incident is 
n — v 
n + v' 
The metal we suppose thick enough for the first surface only 
to be taken into account. 
Putting v — v l — iVo, 
so that and v 2 are positive, the effect becoming zero for z large 
and negative, we have, 
the ratio of the two amplitudes is =— — Vl , 
n + v x — iv o 
and putting this in the form Re l<l> , we have 
(p = tan -1 
2 nv 2 
n 2 — v 2 * — v 2 ’ 
so that the change of phase of the reflected light is, when repre- 
sented as a time, 
1 , . 2 nvo 
- tan -1 — . 
p n 2 — iv — iv 
Now from equation (3), since a = a + ih, and 17 = ~ , 
ay 2 — V 1 — m 2 — iv 5 -f v£ — 0 1 
by 2 + 2v l v. 2 — = 0 j 
Suppose the plane of incidence is that of zx, containing the 
direction of the current. 
