E-StoreCathode ways - light or matter?
4 Jul 2007 20:20:54 IST
Cathode ways - light or matter?
Were cathode rays a form of light, or of matter?
Were cathode rays a form of light, or matter? At first no one really cared
what they were, but as their scientific importance became more apparent,
the light-versus-matter issue turned into a controversy along nationalistic
lines, with the Germans advocating light and the English holding out for
matter. The supporters of the material interpretation imagined the rays as
consisting of a stream of atoms ripped from the substance of the cathode.
Were cathode rays a form of light, or matter? At first no one really cared
what they were, but as their scientific importance became more apparent,
the light-versus-matter issue turned into a controversy along nationalistic
lines, with the Germans advocating light and the English holding out for
matter. The supporters of the material interpretation imagined the rays as
consisting of a stream of atoms ripped from the substance of the cathode.
One of our defining characteristics of matter is that material objects
cannot pass through each other. Experiments showed that cathode rays
could penetrate at least some small thickness of matter, such as a metal foil a
tenth of a millimeter thick, implying that they were a form of light.
cannot pass through each other. Experiments showed that cathode rays
could penetrate at least some small thickness of matter, such as a metal foil a
tenth of a millimeter thick, implying that they were a form of light.
Other experiments, however, pointed to the contrary conclusion. Light
is a wave phenomenon, and one distinguishing property of waves is demonstrated by speaking into one end of a paper towel roll. The sound waves do not emerge from the other end of the tube as a focused beam. Instead, they
begin spreading out in all directions as soon as they emerge. This shows that
waves do not necessarily travel in straight lines. If a piece of metal foil in the
shape of a star or a cross was placed in the way of the cathode ray, then a
?shadow? of the same shape would appear on the glass, showing that the
rays traveled in straight lines. This straight-line motion suggested that they
were a stream of small particles of matter.
is a wave phenomenon, and one distinguishing property of waves is demonstrated by speaking into one end of a paper towel roll. The sound waves do not emerge from the other end of the tube as a focused beam. Instead, they
begin spreading out in all directions as soon as they emerge. This shows that
waves do not necessarily travel in straight lines. If a piece of metal foil in the
shape of a star or a cross was placed in the way of the cathode ray, then a
?shadow? of the same shape would appear on the glass, showing that the
rays traveled in straight lines. This straight-line motion suggested that they
were a stream of small particles of matter.
These observations were inconclusive, so what was really needed was a
determination of whether the rays had mass and weight. The trouble was
that cathode rays could not simply be collected in a cup and put on a scale.
When the cathode ray tube is in operation, one does not observe any loss of
material from the cathode, or any crust being deposited on the anode.
determination of whether the rays had mass and weight. The trouble was
that cathode rays could not simply be collected in a cup and put on a scale.
When the cathode ray tube is in operation, one does not observe any loss of
material from the cathode, or any crust being deposited on the anode.
Nobody could think of a good way to weigh cathode rays, so the next
most obvious way of settling the light/matter debate was to check whether
the cathode rays possessed electrical charge. Light was known to be uncharged. If the cathode rays carried charge, they were definitely matter and
not light, and they were presumably being made to jump the gap by the
simultaneous repulsion of the negative charge in the cathode and attraction
of the positive charge in the anode. The rays would overshoot the anode
because of their momentum. (Although electrically charged particles do not
normally leap across a gap of vacuum, very large amounts of charge were
being used, so the forces were unusually intense.)
most obvious way of settling the light/matter debate was to check whether
the cathode rays possessed electrical charge. Light was known to be uncharged. If the cathode rays carried charge, they were definitely matter and
not light, and they were presumably being made to jump the gap by the
simultaneous repulsion of the negative charge in the cathode and attraction
of the positive charge in the anode. The rays would overshoot the anode
because of their momentum. (Although electrically charged particles do not
normally leap across a gap of vacuum, very large amounts of charge were
being used, so the forces were unusually intense.)
Comments (1)
Naveen
Hot goIITian
Joined: 12 Feb 2007 19:47:24 IST
Posts: 134
4 Jul 2007 23:26:13 IST
Like
0 people liked this
my view is tht thr r only 2 things as matter or wave form...and nothing as light form...in fact light itself has dual nature i.e, both wave and matter form as explained by de broglie..so also de broglie extension any wave can b considered 2 have dual nature so also...cathode rays shud have dual nature..
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