OBJECT: To measure the unknown capacitance by De-sauty bridge.

APPARATUS REQUIRED:

Two Decade Capacitors of  0.1µF total 1µF , An impedance Head Phone , Detecting cables & Bridge Oscillator OMEGA TYPE BO-316.

THEORY:

Looking at the bridge circuit as drawn on the panel of this ECB we see that two arms of  bridge are made up of resistances where as the other arms contain capacitors. Now as we apply an alternating signal (A.C.) from an Oscillator to the two points formed by junction of two resistors and by junction of two capacitors. The capacitors offer some opposition to the applied alternating signal. From A.C theory we know that this opposition is called the capacitive reactance denoted by X_c .the capacitive reactance is given by –

X_c = 1/(2πf_c)

OBJECT: To measure the inductance of a given coil by Anderson Bridge method.

APPARATUS REQUIRED: 

Anderson Bridge circuit, Potentiometer, inductors, capacitors, power supply, connecting wires.

THEORY:

Anderson’s Bridge enables the measurement of inductance in terms of a capacitors and resistance. In experimental arrangement P,Q and R are non inductive resistance arms of the bridge. A non inductive resistance S in series with the given coil of unknown inductance ‘L’ is put in the fourth arm of the bridge between F&D.A variable resistance r and a variable condenser c are put in the parallel to the resistance P .An audio amplifier with speaker is put in between the point ‘E’ and ‘D’ and an audio frequency oscillator with a value control is put between the terminal of ‘A’ and ‘C’. The condition of balance in this case is that the potential at ‘D’ and ‘E’ are same. Under this condition no current flows through path DE and the current in various branches. At balance condition, Using Kirchhoff’s laws we have (in loop ABCD)

OBJECT: To calibrate the given Energy Meter by phantom loading.

APPARATUS REQUIRED:

Energy Meter, Auto Transformer, U.P.F. Wattmeter, Voltmeter, Ammeter, Resistive Load, Stop Watch, Connecting Wires.

THEORY:

Induction type of energy meters are universally used for measurement of energy in domestic and industrial a.c. circuits. Induction type of meters possesses lower friction and higher torque/weight ratio. Also they are inexpensive and accurate, and retain their accuracy over a wide range of loads and temperature conditions. There are four main parts of the operating mechanism:

OBJECT: Measure Earth’s resistance using fall of potential method.

THEORY:

Introduction

The resistance to remote earth of the grounding system needs to be at a minimum in order to sustain its effectiveness.   A few of the components that make up this   resistance   are   the   physical   properties   of   the material used to make the electrode and conductor, all connections made, contact resistance between the electrode  and  the  soil,  and  the  soil  resistivity.     A complete  grounding  system  might  include  only  one earth electrode, an entire group of electrodes with a grounding grid,  or anything  in between  and  beyond. The  earth  electrodes   from  any  of  these  types   of systems can have their resistance to remote earth determined. Theoretically, the resistance to remote earth of an earth electrode can be calculated.   This calculation is based on the general resistance formula: