. Radio-active substances . eding ones. They are deflected by a magnetic field inthe same manner and direction as cathode rays. III. The 7-rays are penetrating rays, unaffected by themagnetic field, and comparable to Rontgen rays. Consider the following imaginary experiment :—Someradium, R, is placed at the bottom of a small deep cavity,hollowed in ablock of lead, p(Fig. 4). A sheafof rays, recti-linear andslightly ex-panded, streamsfrom the re-ceptacle. Let ussuppose that astrong uniformmagnetic field isestablished inthe neighbour-hood of the re-ceptacle, nor-mal to the plane of the figure an
. Radio-active substances . eding ones. They are deflected by a magnetic field inthe same manner and direction as cathode rays. III. The 7-rays are penetrating rays, unaffected by themagnetic field, and comparable to Rontgen rays. Consider the following imaginary experiment :—Someradium, R, is placed at the bottom of a small deep cavity,hollowed in ablock of lead, p(Fig. 4). A sheafof rays, recti-linear andslightly ex-panded, streamsfrom the re-ceptacle. Let ussuppose that astrong uniformmagnetic field isestablished inthe neighbour-hood of the re-ceptacle, nor-mal to the plane of the figure and ^directed to-wards the back. tThe three groups of rays, a, fi, 7, will now be sepa-rated. Then rather faint 7-rays continue in their straightpath without a trace of deviation. The /S-rays aredeflected in the manner of cathode rays, and describecircular paths in the plane of the figure. If the receptacleis placed on a photographic plate, a c, the portion, b c, ofthe plate which receives the ^S-rays is acted upon. Lastly,. Fig. 4. 34 MDME. curies THESIS : the a-rays form a very intense shaft which is slightlydeflected, and which is soon absorbed by the air. Theserays describe in the plane of the figure a path of greatcurvature, the direction of the deflection being the reverseof that with the y8-rays. If the receptacle is covered with a thin sheet of aluminium(o*i thick), the a-rays are suppressed almost entirely,the yS-rays are lessened, and the 7-rays do not appear to beabsorbed to any great extent. Action of the Magnetic Field. We have seen that the rays emitted by radio-activebodies have many properties common to cathode raysand to Rontgen rays. Cathode rays, as well as Rontgenrays, ionise the air, act on photographic plates, causefluorescence, undergo no regular deflection. But thecathode rays differ from Rontgen rays in being deflectedfrom their rectilinear path by the action of the magneticfield, and in the transportation of charges of negativeelectricity. The fac
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1904
