. The Becquerel rays and the properties of radium. Fio. 13.—Another arrangement for observing the magneticdeviation of the ^-^ays. The radium is contained in a smallcapsule, o. Its rays pass through the small hole or siit, b, andfall on a photographic plate or fluorescent screen, c, after passingbetween the poles, d, e, of a magnet. When the current is on,the impression is displaced, and drawn out into an elongatedform, in a direction perpendicular to the paper. 60 THE BECQUEREL EAYS produced by the original undeflected beam. It ismany times broader. We saw in the first chapter that the cathod
. The Becquerel rays and the properties of radium. Fio. 13.—Another arrangement for observing the magneticdeviation of the ^-^ays. The radium is contained in a smallcapsule, o. Its rays pass through the small hole or siit, b, andfall on a photographic plate or fluorescent screen, c, after passingbetween the poles, d, e, of a magnet. When the current is on,the impression is displaced, and drawn out into an elongatedform, in a direction perpendicular to the paper. 60 THE BECQUEREL EAYS produced by the original undeflected beam. It ismany times broader. We saw in the first chapter that the cathode rays,if produced by a steady and uniform discharge, werenot at all spread out by magnetic deflection. Theyare all of the same velocity. With the cathode raysof radium it is otherwise. Their velocities vary overa wide range, some being much more deflected by. Pig. 14.—Magnetic spectrum of /3-rays. Section of the path of the rays. At a theradium is placed in a narrow groove in a piece of metal. The rays pass throughthe slit, b, which confines them to a narrow beam. In the absence of magneticforce, they would fall on the plate at c, in a narrow band. When a magnetic forceis applied perpendicular to the paper, the rays are bent to varying degrees, andreach the plate at various distances, di, (U, d^, from the undeflected a broad band or spectrum is impressed on the plate. magnetic force than others; this explains the broad-ening out of the impression formed by the rays. If we consider the deflected rays which reach somegiven spot on the photographic plate, it is easy tomeasure the circle into which they are bent; for weknow that their path must pass through three points—the narrow radio-active source, the slit, and theassigned spot on the plate (fig. 14). These threepositions being known, it is easy to calculate theradius of
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradiati, bookyear1906
