Chemical effect of current

chemical effect of current 

• Electrolysis :-  सर्वप्रथम मिसाल फैराडे  ने विधुत अपघटन का नियम दिया।  फैराडे के नियमानुसार यदि रासायनिक विलयन में विधुत धरा प्रवाहित की जाये तो विलयन अलग अलग हो जाता है।  या आयनो  में  बंट जाता है इस क्रिया को Electrolysis कहते है। 
• pure distilled water , alcohal , मिटी का तेल  करंट के कुचालक है। 
• dilute acid , dilute alkali , dilute salt  ये करंट के अच्छे चालक है। 
• नेगेटिव इलेक्ट्रोड को कैथोड कहते है तथा धनात्मक इलेक्ट्रोड को एनोड  है। 

faraday's  law 

•  फैराडे ने दो नियम दिए जो की इस प्रकार है  

१. फैराडे का फर्स्ट लॉ :-

 इसके अनुसार ," जिस समय एल्क्ट्रोडे में धरा गुजारी जाती है तो इलेक्ट्रोड अपने आयनो  में विमुक्त हो जाता है।  ये विमुक्त आयन  बहाने वाली धरा एवं जितने समय तक धरा गुजारी गयी के समनुपति होती है। "

m α it

m=Zit (gram)

where Z= आयनो  की संख्या  E.C.E.( Electro chemical equivalent)

i = करंट (amp)

t = धरा गुजरने का समय (sec)

               we know that 

                                            Q= it 

                 so 

                                   m = QZ 

                                                                      continue...............

UPPCL upcoming exam Tg2

दोस्तों जैसा की आप सभी जानते है की आने वाले कुछ महीनो में uppcl Tg2 के लिए भर्ती करने वाला है 

• इसलिए मैंने  यहाँ पर आप सभी के लिए ये ब्लॉगर सुरु किया है।  यहाँ पर आपको हर पाठ  के महत्वपूर्ण पॉइंट्स को बताया जायेगा।  
• फिर उसे रिलेटेड सभी इम्पॉर्टन्ट प्रश्नो को भी बतया जायेगा और पिछले वर्षो में ए हुए सभी प्रश्नो को भी बताया जायेगा। 

• जो की आपके लिए काफी इम्पॉर्टन्ट और लाभदायक भी होगा यह पर मिलें हुए सारे स्टडी मटेरियल को आप तैयार कर लेंगे तो आपको uppcl में Tg2 बनने से कोई नहीं रोक सकता है 
• तो इसके बारे  सबको बातये अपने मित्रो  भी बातये और इसका लाभ उठाए 
• और अगर आपकी कोई भी समस्या हो जो प्रश्नो से सम्बंधित हो या आप कुछ और संसोधन करना कहते हो तो नीचे कमेंट बॉक्स में बातये 

TRANSFORMER

Transformer construction

• There are two types of transformer

1. The core type transformer
2. The shell type transformer

• These two types Transformer are differ from each other in windings.
• The magnetic core is a stack of thin Silicon Steel lamination about 0.35 mm thick for 50 Hz transformer.
• The thin layer are varnish to reduce the Eddy current losses
•  For core losses (which are made from C.R.G.O.  (cold rolled grain oriented sheet Steel.)). This material has low core loss and high permeability

1.Core type transformer

• The windings surround a considerable part of Steel core.
• For a given output and voltage rating it requires less iron but more conductor material.
• Most of the flux is confined to high permeability core  but some leakage flux flows through the core legs and nonmagnetic materials surrounding the core. For avoiding it half of the low voltage (L.V.) winding is placed over one leg and other half over the second limb. 
• Low voltage windings are placed adjacent to steal core and high voltage winding outside in order to minimise the amount of insulation required.
•  it performs better for high voltage high power levels

2.Shell type transformer

• In this type of Transformer the LV and HV winding are wound over the central Limb and are inter leaved or sandwiched. it performs better for low voltage low power levels where as cool type to construction is used for a high voltage high power transformer
• Lower power transformer are air cooled where as large power transformer are immersed in oil for better cooling
• In iron core Transformers most of the flux is confined to high permeability Core. there is however some flux that leaks through the core legs and non-magnetic materials surrounding the core. this flux called leakage flux links one winding and not the other.

Note:- there are two types of windings employed for Transformers. the concentric coils are used for core type Transformers as shown in the above figure. and interleaved coils  for shell type transformer as shown in the above figure.

• Low power transformers are air cooled where as large power transformer are immersed in oil for better cooling in oil cooled Transformer the oil serves as a coolant and also as an insulating medium
• For power frequency range of 25 to 400 Hz transformers are constructed with 0.35 mm thick Silicon Steel laminations
• For audio frequency range of 20 to 20000 Hz iron core with suitable refinement is used
• For high frequency employed in communication circuits who is made up of powered ferromagnetic alloy.
• In special cases the magnetic circuit of a transformer may be made of non magnetic material and in such a case the transformer is referred to as an air core transformer
• The Air core transformer is Primarily used in radio devices and in certain types of measuring and testing instruments.
• Core made of soft ferrites are also used for pulse Transformers as well as for a high frequency electronics Transformers.

TRANSFORMER

TRANSFORMER

• The transformer is a device that transfers electrical electrical energy from one electrical circuit to another electrical though the medium of magnetic field and without a change in the frequency.
• Transformer is an electromagnetic energy conversion device since the energy received by the primary is first converted to magnetic energy and it is then he converted to useful electrical energy in the other circuit.
• Thus primary and secondary winding of a transformer are not connected electrically but are coupled magnetically.
• The step up Transformer have more secondary winding turns in comparison to primary winding i.e. the secondary voltage is higher than the primary voltage.
• The step down Transformer have less secondary winding turns in comparison to primary winding i.e. the secondary winding voltage is lesser than the primary voltage.
• In a transformer the electrical energy transfer from one circuit to another circuit takes place without the use of moving parts it has therefore the highest possible efficiency out of all the electrical machine and requires almost negligible amount of maintenance.
• Transformer is widely used in prominent areas of electrical engineering.

1. In communication system input Transformer connected the microphone output to the first stage of an electronic amplifier.
2. It is used in radio and television circuit.

• In electronic and control circuit Transformer are used for Impedance Matching for maximum power transformer from source to the load.
• Pulse Transformer are used in application in radar and digital computer.
• In power electronics it is used widely which is given below

1. For GATE pulse triggering
2. For synchronising the pulse getting signals with AC supply voltage given to the main power circuit 

To be continue.........

UPPCL Questions

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Q1:-In a series a.c. circuit the voltage across a pure capacitor is 12V and the voltage across a pure resistance is 5V. Then the supply voltage will be _________.

13V 
17V 
7V 
2.7V

ANSWER:-13V 

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Q2:-What will be the largest number of 100W electric light bulbs which can be operated from a 200V supply fitted with a 13A fuse?

16 
26 
31 
32 

ANSWER:-26

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Q3:-A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD) current of 0.6mA with shunt resistance of 1 ohm. Current through the meter at 0.5 F.S.D is:-

0.007mA 
0.05mA 
0.3mA 
0.01mA 

ANSWER:-0.3mA

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Q4:-A time–varying flux causes an induced electromotive force". What law does this statement represent?

1.Ampere's law
2.Faraday's law
3.Lenz's law
4.Field form of Ohm's law

ANSWER:-Faraday's law 

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Q5:-In a 3 phase controlled bridge rectifier,each thyristor conducts for the period of maximum of _____________.

60 degree 
180 degree 
120 degree 
90 degree 

ANSWER:-120 degree 

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UPPCL Questions

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Q1:-The maximum power developed by a synchronous motor depends on ________________ & _________________.

1. Supply voltage, Maximum value of load angle  
2. Supply voltage, Excitation current  
3. Excitation current, Maximum value of load angle
4. Output voltage,Supply frequency 

ANSWER:-Supply voltage, Excitation current

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Q2:-The Anode current through a conducting SCR is 12 A. If its gate current is made one-third, then find Anode current.

1.5A 

2.4A 

3.0A 

4.12A 

ANSWER:- 0A 

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Q3:-Assertion (A): It is possible to design a current source using operational amplifier
Reason (R): Operational amplifier is a current controlled voltage source
1.Both A and R are individually true and R is the correct explanation of A
2.Both A and R are individually true but R is not the correct explanation of A
3.A is true but R is false
4.A is false but R is true 

ANSWER:-A is true but R is false 

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Q4:-A 220V, 100W lamp has a working resistance of:-

2.2Ω
480Ω
960Ω
484Ω

ANSWER:-484Ω

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Q5:-Eddy current loss in a transformer is proportional to:-

1.Frequency
2.Supply voltage
3.Square of the frequency
4.Square of the voltage only

ANSWER:-Square of the frequency 

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UPPCL Questions

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Q1:-A moving coil of a meter has 400 turns and a length and depth of 20 mm and 20 mm respectively. It is positioned in a uniform radial flux density of 200 mT. The coil carries a full scale current of 25 mA. The torque on the coil is ____________________ and sensistivity is _____________________ 

1.800 μNm , 40 Ω/V 
2.800 μNm ,25 Ω/V 
3.200 μNm ,100 Ω/V 
4.800 μNm,1 Ω/V 

ANSWER:-1

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Q2:-In a three phase half wave rectifier feeding resistive load, if the input source is a three phase 4 wire system and line to line voltage is 100 V. The supply frequency is 400 Hz. The ripple frequency at the output is:-

1.400 Hz

2.600 Hz

3.1200 Hz

4.800 Hz

ANSWER:-3

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Q3:-The measurement range of an voltmeter can be increased by using a ________.

1.High resistance in shunt 
2.Low resistance in shunt
3.High resistance in series
4.Low resistance in series 

ANSWER:-3

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Q4:-Two single-phase transformers A and B with equal turn ratio have reactances of j3 Ω and j9 Ω referred to secondary. When operated in parallel, the load-sharing of 200 kW at 0.8 pf lag between A and B transformers would respectively be:-

1.75 kW and 25 kW
2.100kW and 100 kW
3.150 kW and 50kW
4.120 kW and 80 kW 

ANSWER:-3

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Q5:-Surge impedance loading of a transmission line can be increased by:-

1. Decreasing its voltage level
2. Reducing the length of the line

Only 2 is correct 
Only 1 is correct 
Both 1 & 2 is correct 
Both 1 & 2 is incorrect 

ANSWER:-Only 2 is correct 

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