KIDNEY STONES

KIDNEY STONES:

Types of Kidney Stones depending on their location
1)Renal Stones
2)Calyceal Stones
3)Ureteral Stones

Renal Stones are located in the kidney.
Calceal Stones are located between the kidney and ureter
Ureteral Stones are in the tube that drains urine from kidney to the bladder.

Calyceal stones are found in the funnel shaped area called calyx between kidney and ureter.

HOW TO BACK UP SYSTEM REGISTRY

BACK UP OF SYSTEM REGISTRY:

Before making any changes to your windows registry,
you should back up copy of key or sub key of the registry.  Save the back up copy of the registry to a desired location (export).  

If you want to retrieve back the registry settings, when your changes to the registry went wrong, you can import back up copy, that restores your system registry back to the previous stage.

To back up registry you must login as an administrator, open the registry editor by clicking start button and type "regedit" in the search box, and press.  Locate and click the key or sub key that you want to back up.  Click the file menu, and then click export.  In the save in box, give the file name and location and click save.

WHAT IS REGISTRY

REGISTRY:

Registry is a database in Windows operating system that stores information about installed programs, system hardware and settings, user accounts etc.,
Registry automatically updates when you install new softwares, applications etc.,  No need to change manually.  An incorrect change to registry may lead to the computer inoperable.  Back up the registry before making any changes manually.

WHAT IS POST SCRIPT FILE

POST SCRIPT FILE:

Post Script, is primarily a programming language for printing documents on laser printers. Post Script file is a type of printing format.  .ps is the extension for the post script file.  when you print a document into a post script format it maintains all the graphics, fonts, images into a unique pack.  To create a post script file you should have installed post script driver into your computer.

WHAT IS ACROBAT DISTILLER

ACTROBAT DISTILLER:

Acrobat Distiller software is used to create PDF files. PDF files created with Acrobat Distiller maintain all the graphics, formats,images of the original document.  The Most reliable method for creating PDF files.  It involves printing a document into a  Post Script file (.ps).  And then converting a .ps file into a PDF file.  When you Create a .ps file,  all the graphics, formats, text, images converted into a pack. 

WHAT IS BY-PASS FACTOR

BY-PASS FACTOR:
It is defined as the ratio of the difference between the mean surface temperature of the coil and leaving air temperature  to the difference between the mean surface temperature of the coil and leaving air temperature.

WHAT IS SENSIBLE HEATING

SENSIBLE HEATING:
When air passes over a dry surface which is a temperature greater than its dry bulb temperature, it (air) undergoes sensible heating. During sensible heating specific humidity remains constant. During this process dry bulb temperature of air raises and approaches that of dry surface.

SENSIBLE HEAT AND LATENT HEAT

SENSIBLE HEAT:
It is the heat that changes the temperature of a substance when it added to or removed from it.

LATENT HEAT:
It is the heat that does not affect the temperature but changes the state of a substance when added or removed from it.

WHAT IS SYSTEM, BOUNDARY AND SURROUNDINGS

SYSTEM:
A System is a Finite quantity of matter
(or)
Prescribed Region of Space

BOUNDARY:
The actual or hypothetical envelope enclosing the system is called boundary. The boundary may fixed or may move. The boundary may be real or imaginary

SURROUNDINGS:
Everything outside the boundary is called surroundings

HOLDING CURRENT

HOLDING CURRENT
It is the maximum anode current, gate being open, at which SCR is turned off from ON conditions.

When Semi conductor Rectifier is in the conducting state, it cannot be turned OFF even if gate voltage is removed.  The only way to turn off or open the SCR is to reduce the supply voltage to almost zero at which point the internal transistor comes out of saturation and opens the SCR.  The anode current under this condition is very small (few mA) and is called Holding current.  If an SCR has a holding current of 5mA, it means that if anode current is made less than 5mA, then SCR will be turned off.

PEAK REVERSE VOLTAGE

PEAK REVERSE VOLTAGE
It is the maximum reverse voltage (cathode positive w.r.t anode) that can be applied to an SCR without conducting in the reverse direction.

Peak reverse voltage(PRV) is an important consideration while connecting an SCR in an a.c circuit. During the negative half of a.c supply, reverse voltage is applied across SCR.  If PRV is exceeded, there may be avalanche breakdown and the SCR will be damaged if the external circuit does not limit the current.  

BREAKOVER VOLTAGE

BREAKOVER VOLTAGE
It is the minimum forward voltage, gate being open, at which  Semi Conductor Rectiver(SCR) starts conducting heavily i.e turned on

if the breakover voltage of an SCR is 220V, it means that it can block a forward voltage as long as the supply voltage is less than 220V.  If the supply voltage is more than this value, the SCR will be turned on.  In practice SCR is operated with supply voltage less than breakover voltage and it is then turned on by means of a small voltage applied to the gate.

SILICON CONTROLLED RECTIFIER (SCR)

SILICON CONTROLLED RECTIFIER (SCR)
is a semiconductor device that acts as a true electronic switch.  It can change alternating current into direct current and at the same time can control the amount of power fed to the load.  SCR combines the features of a rectifier and a transistor.

MERITS AND DEMERITS OF MULTIMETER

Multimeter is widely used for manufacturing and servicing of electrnoics equipment.  It has its own merits and demerits.

Merits:
It has a single meter which performs several measuring functions
it can make measurements with reasonable accuracy

Demerits:
It cannot make precise and accurate measurements due to the loading effect
Technical skill is required to handle it.

WHAT IS MULTIMETER SENSITIVITY

The resistance offered per volt of full scale deflection by the multimeter is known as multimeter sensitivity. it indicates the internal resistance of the multimeter.  If the sensitivity of a multimeter is high, it means that it has high internal resistance. when such a meter is connected in the circuit to read voltage, it will draw a very small current.  if the sensitivity is low, it would cause serious error in voltage measurement.

WHAT IS MULTIMETER

Multimeter is an electronic instrument used for measuring resistances, current and voltages. it can be used for measuring D.C aswell as A.C voltages and currents.

WHAT ARE THE APPLICATIONS OF MULTIMETER

A multimeter is used for
1)checking the circuit continuity.
2)measuring d.c. voltages across various resistors in electronic circuits.
3)measuring d.c current flowing through the cathode, plate, screen and other vacuum tube circuits
4)measuring a.c. voltages across power supply transformers
5)ascertaining whether or not open or short circuit exists in the circuit.

APPLICATIONS OF VTVM

A VTVM is used for 
1) D.C Voltage measurements:
A VTVM can accurately measure the D.C voltages in an electronic circuits.  

2)D.C Current Measurements:
VTVM does not incorporate a current scale, however current values can be found indirectly.

3)A.C voltage Measurements:
For measuring A.C voltage, a rectifier is used in conjunction with a VTVM.

4)Resistance measurements:
VTVM has ability to measure resistance upto 100 M ohms

VACUUM TUBE VOLTMETER (VTVM)

VTVM is extensively used for measuring both A.C and D.C voltages.  The Vacuum tube voltmeter has high internal resistance (>10 M ohms) and draws extremely small current. The loading effect is very small. A VTVM measures the exact voltage even across a high resistance.  A vacuum tube voltmeter consists of voltmeter and electron tubes.

WHAT IS DIAC

A Diac is a two terminal, three layer bidirectional device which can be switched from its OFF state to ON state for either polarity of applied voltage.  The diac can be constructed in either npn or pnp form.