2. It is a device used for building up extremely high Potential
Differences in the order of a few million (as high as 20 million
volts). Currently, Van de Graaff Generator produces a Potential
Difference of 5 Mega volts.
The Van de Graaff Generator was designed by Robert Jemison
Van de Graaff in1929 A.D.
While standing on an insulated platform, if we touch the
spherical part of this Generator, the charge of the sphere would
pass along our body and would transmit to our hairs.
Since the same charge would produce on our hairs, and these
charges would repel each other. This is what we could see in the
picture below:
Van de Graaff Generators are delineated as the "constant
current" electrostatic devices. When we put a load on a Van de
Graaff Generator, the current remains constant., but the
voltage alters with the load.
Van de Graaff Generator
3. Van de Graaff Generator is one of the devices that has
an insulating effect and helps insulate various objects by
creating a very high Potential. There is the acceleration
of particles that are observed. There is also the presence
of atom smashers where the subatomic particles are
exposed to high-speed acceleration and are then
smashed into the target atoms. Due to this smash
collision happening there is the production of other
subatomic particles along with other high energy
radiation being produced.
Introduction:
4. The triboelectric effect is a type of electrification in
which certain materials tend to become charged
electrically when they come into contact with one
another and are then separated from each other. The
polarity and strength of the charges that are being
produced may differ in magnitude based on the
materials that are used, surface roughness,
temperature, strain, and other properties.
Triboelectric Effect Seen in Van De
Graaff Generator:
5. Van de Graaff Generators are
“Constant Current”
Electrostatic devices that
work mainly on the two
principles: Corona discharge.
Accumulation of charge on
the outer sphere.
Principle
6. An outer terminal - An aluminum or
steel sphere
Upper brush - A piece of fine metal
wire
Upper pulley (P1) - A piece of nylon
A long narrow conveyor belt of
insulating material like Silk, rayon or
rubber wound around the pulleys P1
and P2
Motor
Lower brush
Lower pulley (P2) - A piece of nylon
covered with silicon tape.
B1 - Sharply pointed spray comb
B2 - Sharply pointed collecting comb
Van De Graaff Generator
Consists of the Following:
7. When the spray comb is given a positive Potential (= 104 volts) w.r.t. the
earth via the high tension source H.T. Due to corona discharge action of
sharp points, a positively charged electric wind is set up, which sprays a
positive charge on the belt as soon the motor is turned on, the lower
pulley (P2) begins turning the positively charged belt upwards, and the
lower pulley (P1) establishes a negative charge. Since the pulley P2 is
capturing electrons from the belt which is passing over this pulley P2.
Here, we can see that the charge on the pulley P2 is more concentrated
than the belt because a strong electric field is generated at the lower
pulley.
As the belt reaches the sphere, a negative charge builds upon the
collecting comb B2 and a positive charge on the farther side of the comb
B2.This positive charge shifts to the outer surface of S.
The discharging action of sharp points of the comb B2, a negatively
charged electric wind is set up. Which in turn would neutralize the
coated positive charge on the belt, and the belt would turn down again.
Working
8. Particle Accelerators
These accelerators are also known as Particle Smashers. The
high energy supply by the Generator accelerates the subatomic
particles in an evacuation tube, and these particles crash into
atoms.
The ability of a Generator to create these high-energy collisions
is the cornerstone of Particles and used to accelerate ions,
protons, and electrons needed for various experiments of
Nuclear physics.
These Generators are used as accelerators to generate X-Ray
beams for nuclear research and nuclear medicine.
Science Education In physics education to teach Electrostatics.
Sterilizing Food Accelerates electrons to sterilize food and
process materials
Uses of Van de Graaff Generator
9. There are two kinds of Van de Graaff Generators: The
one employs high-voltage power supply for charging
and one utilizes belts and rollers for charging.Van de
Graaff Generator, as we set about the output terminal
(sphere) with a grounded object, the voltage will
decrease, but the current will remain the same. The
charges are produced due to friction by two insulating
bodies rubbing against each other, and they can’t
move on their own (at rest) which means they
(charges) are static by nature are called Static charges.
Summary