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8/7/2019 Vaan de Graaf Generator
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Van De Graaff GeneratorPRINCIPLE
THEORY
CONSTRUCTION
WORKING
&APPLICATIONS
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The device has the ability to produce
extremely high voltages-as high as 20
million volts
The generator is to supply the high
energy needed for early particle
accelerators
These accelerators are known as
atom smashers .
The resulting collision created
other sub atomic particles and highenergy radiations such as X-rays.
The ability to create these high energy collisions is
the foundation of particle and nuclear physics.
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Principle
Working of the generator is based on twoprinciples:
I. Discharging action of sharp points i.e., electric
discharge takes place in air or gases readily at pointed
conductors.
II. If the charged conductor is brought in to internalcontact with a hollow conductor, all of its charge
transfers to the surface of the hollow conductor no
matter how high the potential of the latter may be.
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Theory behind construction:
If we have a large conducting spherical shell ofradius R on which we place a charge Q, it spreadsitself uniformly all over the sphere. The field outsidethe sphere is just that of a point charge Q at the
centre; while the field inside the sphere vanishes.
So the potential outside is that of point charge andinside it is constant.
The potential inside the conducting sphere =
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Now suppose that we introduce a small sphere of
radius r, carrying a charge q, into the large one and
place it at the centre. The potential due to this newcharge has following values.
Potential due to small sphere of radius r carrying
charge
at the surface of small sphere
at the large shell of radius R
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Taking both charges q and Q in to account we have
for the total potential V and the potential differencegiven by
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Construction
Details
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ightening / sparking produced in
Van De Graaff Generator
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Demonstration of
Van De Graff Generator
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Sparks up to 35 cm in Length
A Large Sphere Creates Higher Voltage
A Large Size Ideal for Demonstrations
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This science-show Van
de Graaff Generator can
deliver a spark over 48"
long. The generator is 10'
tall and has a 42"
diameter collector.
The author constructed
the machine in 1988 for
The Science Place
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The High Voltage Van de Graaff
Generator features a 25 cm
diameter sphere which can
generate approximately 400,000
Volts.
The size of the sphere, therounded edges of the sphere and
the height of the sphere from the
demonstration table contribute to
the high voltages generated.
Its large size, long sparks and
high voltages make it ideal for use
in larger rooms or lecture halls.
An extra belt is included.
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Fig - A horizontal Van de
Graaff generator
constructed for a company
investigating effects of static
electricity on aircraft
components.
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