## Megger method for measurement of high resistance

Construction- A megger is a portable device which is used for the measurement of high resistance. The component of megger are Permanent magnet C shaft Hand driven generator Resistances RC and RD Two Coils- Control coil (Cs) Deflection Coil (Cd) Working Principle- As current provided by the hand driven generator Read more…

## Direct deflection method for measurement of high resistance

From fig 1 we are going to measure the resistor value of a cable with outer metallic sheath available. The galvanometer measures the current between the outer sheath and the conductor current. The galvanometer is very much sensitive to the current because the current value is in the range of Read more…

## Voltmeter-Ammeter method for measurement of medium resistance

In the figure let us assume the voltmeter to be ideal (internal resistance Rin=infinite). So current Iv=0A I= IA+IV I=IA       [IV=0A] V=VA+VK V=I×RA+I×Runknown Ammeter is  not ideal here. V=I(RA+ Runknown) V/I= RA+ Runknown            [V/I= Measured value of resistance] RM=RA+ Runknown So the measured value of resistance is greater than the Read more…

## Method of substitution for measurement of medium resistance

E= External battery R= resistance to be measured S= Variable resistance R= Turning resistance Sw= Switch A= Amperemeter The position of the switch is at a point 2 with the battery E makes a close loop with resistance r, ammeter and the unknown resistance R. There will be a deflection Read more…

## Wheatstone bridge method for measurement of medium resistance

Wheatstone bridge- Balanced Bridge condition R1/R2=R3/R4 I1=I3 and I2=I4 Vbc=Vde and Vab=Vad Vbc=I3R3 Vdc=I4R4 As        Vbc=Vdc I3R3=I4R4 I3/I4=R4/R3 Vab=I1R1 and Vad= I2R2 As        Vab=Vad I1R1=I2R2 I1/R2=I2/R1 As        I3=I1 and I2=I4 I3/I4=I1/I2 R4/R3=R2/R1 R1/R2=R3/R4 R3=R4×R1/R2      (Proved)  Advantages- It can measure the medium range resistance (1 Ω <R<1 kΩ). The design is comparatively Read more…

## Measurement of resistance

Measurement of resistance- Properties of resistance plays an important role in determining performance specification for various circuit elements including coil, winding, insulation etc. Apart from this resistor are use as standard for measurement of other unknown resistances and for the determination of unknown inductance and capacitance. For the point of Read more…

## What is Error, types and source of error

Error and types of error- Error is the deviation of the measured value from the desired value. It is also called as absolute error. If          Yn=desired value Xn= measured value e=absolute error Then e can be defined as        e= Yn– Xn Types of error- Error can  be categorized into 3 Read more…

## Different methods of measurement

Different methods of measurement- There are two methods of measurement- 1. Direct measurement method 2. Indirect measurement method Direct measurement method- Direct comparison with standard In this method of measurement, we compare the quantity with primary standard or secondary standard. Ex- If we have to measure the length of a Read more…