Voltage dependent resistor, Physics

Assignment Help:

A VDR is a special type of resistor that changes its resistance with rise in voltage. It has a very high resistance at low voltage (below the trigger voltage) and very low resistance at high voltage (above the trigger voltage). It is also called varistor or voltage sensitive resistor. There are two types of varistor.

SILICON CARBIDE VARISTOR:-              

MANUFACTURING: These are made up of silicon carbide. It is milled and mixed with a suitable ceramic binder. Then it pressed and extruded to desired shape of disc, rod or washer. Then it is sintered under controlled temperature to produce hard material. Wire leads are then connected.

METAL-OXIDE VARISTOR (MOV):

MANUFACTURING:

 Zinc oxide and bismuth oxides are mixed with other powdered metal additives, pressed into discs and sintered at 12000C. It has an encapsulated polycrystalline ceramic body; with metal contacts and wire leads.

APPLICATIONS: A varistor acts as a switch. It is usually used for short circuit protection in power strips or lightning bolts "arrestors" on street power poles. It is also used as a "snobbier" in inductive circuits.

 


Related Discussions:- Voltage dependent resistor

Work power energy, A block of mass 2 kg is pulled up on a smooth incline ma...

A block of mass 2 kg is pulled up on a smooth incline making angle 30 degrees with horizontal . if block moves with an acceleration of 1 m/s2 , find a) Power delivered by the pull

Maxwells equations, Maxwell's equations (J.C. Maxwell; 1864): Four ele...

Maxwell's equations (J.C. Maxwell; 1864): Four elegant equations that describe classical electromagnetism in its entire splendor are following.

Determine the focal length of the lens, Q. A screen is placed 90 cm from an...

Q. A screen is placed 90 cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20cm. Determine the focal lengt

Existing electric field, 12 joule of work has to be completed against an ex...

12 joule of work has to be completed against an existing electric field to take a charge of 0.01 C from A and B. How much is the potential difference VB-VA.

Moving coil galvanometer, sensitivity of moving coil galvanometer can be in...

sensitivity of moving coil galvanometer can be increased by decreasing?

Define an echo sound, An echo is easily the retransmission of speaker's ow...

An echo is easily the retransmission of speaker's own voice caused by reflection at a distance surface. If there is a sound reflector at a distance d from host, then the time in

Calculate the fringe width, Q. In Young's double slit experiment, the width...

Q. In Young's double slit experiment, the width of the fringe obtained with light of wavelength 60000A is 2 mm. Calculate the fringe width if the entire apparatus is immersed in a

Frequency dependence of dielectric constant, E lectrons have very much smal...

E lectrons have very much smaller mass than that of ions, so they respond more rapidly to a changing electric field. For electric field that oscillates at extremely high frequencie

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd