CYCLOTRON

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CIRCULAR COIL

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MILLIKAN OIL DROP

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ROBERT MILLIKAN,MARCH 22,1868

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YOUNG'S DOUBLE SLIT

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thomas young,june 13,1773

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EFFECT OF FREQUENCY

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GRAPH,2

VAN DE GRAAFF

VAN DE GRAAFF GENERATOR:

PRINCIPLE: 

  *IT WORKS ON THE PRINCIPLE OF ELECTROSTATIC INDUCTION AND ACTION OF POINTS.

CONSTRUCTION:

 * 'A' BE THE HOLLOW METALLIC SPHERE MOUNTED ON INSULATING PILLARS.

 * 'B' AND 'C' BE THE TWO PULLEYS.'B' IS MOUNTED AT THE CENTRE OF THE SPHERE AND 'C' IS MOUNTED NEAR THE BOTTOM.


 * PULLEY 'C' IS DRIVEN BY AN ELECTRIC MOTOR.


 *A SILK BELT MOVES OVER THE PULLEYS.

 *'D' AND 'E' BE THE TWO COMB SHAPED CONDUCTORS HAVING SHARP NEEDLES WHICH ARE MOUNTED NEAR THE PULLEYS.


 *COMB 'D' IS GIVEN A POSITIVE POTENTIAL (10^4 V) BY A POWER SUPPLY.


 *COMB 'E' IS CONNECTED TO THE INNER SIDE OF THE HOLLOW SPHERE.

WORKING:

 *SINCE HIGH ELECTRIC FIELD IS AT 'D' AIR GETS IONISED DUE TO ACTION OF POINTS.

 *NOW THE NEEDLE ATTRACTS NEGATIVE CHARGES AND REPELS POSITIVE CHARGES TOWARDS THE BELT.

 *THE POSITIVE CHARGES STICK TO THE BELT, MOVES UP AND REACHES 'E'.


 *'E' ACQUIRES NEGATIVE CHARGES DUE TO ELECTROSTATIC INDUCTION AND SPHERE ACQUIRES POSITIVE CHARGES  WHICH ARE DISTRIBUTED ON ITS OUTER SURFACE.

  *THE HIGH ELECTRIC FIELD AT 'E' IONISES THE AIR AND HENCE NEGATIVE CHARGES ARE REPELLED TOWARDS THE BELT.


 *DUE TO THIS THE POSITIVE CHARGES ARE NEUTRALISED BEFORE THE BELT MOVES OVER THE PULLEY.

 *SO THE DESCENDING BELT IS LEFT UNCHARGED.


 *THE POTENTIAL OF THE  SPHERE KEEPS ON INCREASING AND REACHES A MAXIMUM OR LIMITING VALUE.


 *AFTER THIS STAGE LEAKEGE OF CHARGES OCCUR DUE TO IONISATION OF AIR.

ROBERT J.VAN DE GRAAFF

 *THIS LEAKAGE CAN BE REDUCED BY ENCLOSING  THE MACHINE IN A GAS FILLED STEEL CHAMBER AT A VERY HIGH PRESSURE.

USES:

 *USED TO PRODUCE LARGE ELECTROSTATIC POTENTIAL DIFFERENCE UP TO 10^7  V.

 *THIS HIGH VOLTAGE IS USED TO ACCELERATE THE POSITIVE IONS (PROTONS,DEUTRONS ) FOR NUCLEAR FISSION PROCESS.


 

VOLTAIC CELL

ALESSANDRO VOLTA

VOLTAIC CELL :

*IT IS A SIMPLE CELL WHICH CONVERTS CHEMICAL ENERGY IN TO ELECTRICAL ENERGY.

*ANODE - COPPER
 CATHODE - ZINC
 ELECTROLYTE - Dil.H2SO4
 EMF - 1.08 V

*IONISATION TAKES PLACE AT THE CATHODE.

*TWO ELECTRONS LEFT AT THE CATHODE AND Zn IONS PASS IN TO THE SOLUTION i.e.,

Zn + Dil.H2SO4 ------> ZnSO4 + 2H + 2 electrons

*TWO HYDROGEN IONS ARE DISCHARGED AT THE ANODE. CURRENT FLOWS CONTINUOUSLY IN THE EXTERNAL CIRCUIT AS LONG AS ELECTRONS  ARE AVAILABLE AT THE CATHODE.


*WHEN THE ELECTRODES ARE CONNECTED BY A WIRE EXTERNALLY, CURRENT FLOW FROM COPPER TO ZINC OUTSIDE THE CELL AND CURRENT FLOWS FROM ZINC TO COPPER INSIDE THE CELL.


*DUE TO OPPOSITE CHARGES ON THE TWO ELECTRODES A POTENTIAL DIFFERENCE IS PRODUCED BETWEEN COPPER AND ZINC WHERE COPPER IS AT HIGHER POTENTIAL THAN ZINC.

LEAD ACID ACCUMULATORS

LEAD ACID ACCUMULATOR:

GASTON PLANTE

*IT IS ONE OF THE SECONDARY CELLS.

*ANODE - PbO2 ( LEAD OXIDE )
  CATHODE - SPONGY LEAD (Pb)
  ELECTROLYTE - Dil.H2SO4
  EMF - 2.2 V
  SPECIFIC GRAVITY OF THE ELECTROLYTE - 1.28

*THESE ARE PLACED IN A CONTAINER MADE UP OF HARD RUBBER OR GLASS OR CELLULOID.

*THE ELECTRODES ARE SEPARATED BY INSULATING MATERIALS AND ASSEMBLED TO GIVE LOW INTERNAL RESISTANCE SO THAT HIGH CURRENT IS DELIVERED.

WORKING

*AS THE CELL IS CONNECTED IN A CIRCUIT EXTERNALLY OXIDATION REACTION TAKES PLACE AT THE CATHODE.

*SPONGY LEAD REACTS WITH Dil.H2SO4 AND PRODUCES PbSO4 AND TWO ELECTRONS.
        Pb (SPONGY) + Dil.H2SO4 -----> PbSO4 + 2 electrons

*ELECTRONS FLOW FROM CATHODE TO ANODE EXTERNALLY ( REDUCTION REACTION TAKES PLACE AT THE ANODE )

*PbO2 REACTS WITH Dil.H2SO4 AND PRODUCES PbSO4 i.e.,
       PbO2 + Dil.H2SO4 ------> Pb(SO4)2 +2H2O

*TWO ELECTRONS  AND Pb IONS ARE NEUTRALISED IN THIS PROCESS.

*NOW THE CURRENT FLOW FROM ANODE TO CATHODE.

*AS THE CELL IS DISCHARGED BY DRAWING CURRENT FROM IT, THE EMF FALLS TO ABOUT 2 VOLTS.

*DURING CHARGING PROCESS CHEMICAL REACTIONS ARE REVERSED.


*

LECLANCHE CELL

LECLANCHE CELL:

* IT IS A PRIMARY CELL

* IT IS USED FOR SUPPLYING INTERMITTENT CURRENT

* ANODE - CARBON ELECTRODE ( PACKED IN A POROUS POT CONTAINING MnO2 + CHARCOAL POWDER )
   CATHODE - ZINC ROD
   ELECTROLYTE -NH4Cl ( IN WHICH ANODE & CATHODE ARE IMMERSED )
   EMF - 1.5 V

GEORGES LECLANCHE

                                                CURRENT - 0.25 A

*DUE TO OXIDATION REACTION ZINC REACTS WITH AMMONIUM CHLORIDE GIVING OUT Zn IONS AND 2 ELECTRONS i.e.,

*Zn + 2NH4Cl -----> 2 NH3 (GAS) + ZnCl2 + 2 H + 2 electrons

( OXIDATION REACTION TAKES PLACE AT THE CATHODE )

*AMMONIA GAS ESCAPES AND H2 IONS DIFFUSE THROUGH THE PORES OF POROUS POT AND REACT WITH MnO2.

*2 HYDROGEN IONS DISCHARGED AT THE ANODE.

*WHEN THE CELL IS CONNECTED BY A WIRE EXTERNALLY TWO ELECTRONS ON THE Zn ROD PASS THROUGH THE EXTERNAL CIRCUIT AND REACH THE CARBON ROD NEUTRALISING THE POSITIVE CHARGE.

*THUS CURRENT FLOW FROM CARBON TO ZINC.