Tuesday 16 October 2012

ELECTRICITY AND ITS FUNDAMENTAL LAWS


SHORT ANSWER QUESTION

Q: 1.In an atom,nucleus has proton and neutron.

     What are the charges proton and neutron having?
Ans: 1. proton-positive charge, Neutron-no charge.

Q: 2.An atom contains three particles.They are protons neutrons and electrons.

       Which particle has excess of holes?
Ans: 2.Proton.

Q:3.The outer most orbit an atom has more than 4 electrons,that susbtance is called as insulator.

       How many electrons should be in the outer most orbit of the semi-conductor atom?
Ans: 3. 4

Q: 4. When the current is passing through any media, some effects will happen.

       What will happen, when the current is passing through a spirally wound coil?
Ans: 4. magnetic.

Q:5. When the current with high frequency is passed through vacuum tube, some effect will occur.

      What is the name of effect?
Ans: 5. x-ray.

Q:6. the leakage current is the cause for electric shock in human beings.

       what is the minimum current level to get electric shock for normal human body as per IE regulation?

Ans: 6. Beyond 5 milliampere.

Q: 7. Resistance of any substance depends upon four factors. Three factors are given below.
       1.length of the conductor.
       2.Area of cross section.
       3.Temperature.

      What is fourth factor?
Ans: 7. specific resistance.

Q: 8. Resistance of the conductor depends upon various factors.

        what will happen to the value of resistance of conductor ,if its diameter is halved ?
 Ans: 8.increased ti twice
 
Q: 9. resistance of the conductor depends upon with temperature of  some material is increased its resistance                            
        also decreased
        In what term the above materials are called

Ans: 9.negative temperature co-efficient material

 Q:10. copper ,aluminum,iron  and silver are used as electrical conductor.
         Arrange the above four conductors according to their resistance value in an ascending order.
Ans:10. silver,copper ,aluminium,iron

Q:11. the property of opposition to the flow of current through a conductor is know as resistance .
          a) what is the term called the reciprocal of resistance ?
          b) what its unit?

Ans:11. conductance, Mho or scimens

Q:12. Every metal conductor has its own specific.
          what is the value of specific of copper ?
Ans:12. 1.72X10    ohm -m

 Q:13. The specific resistance of the conductor is inversely proportional to its section area.

          What is the value of resistance of conductor, if its length is doubled?

Ans:13.2 Times increase in resistance value.

Q:14. when a temperature of a conductor is increased the resistance of the conductor is also increased.

     a) what type of temperature co-efficient is it?
     b) Give an example to this?

Ans:14. a) Positive temperature co-efficient.
             b) Silver.

Q:15. when the temperature of the substance is increased to one degree centigrade. its resistance
            is decreased to a certain value.

      a) how does the substance called?
      b) Give one example for it.

Ans:15. a) Negative temperature co-efficient.
            b) carbon.

Q:16. In a circuit, when one ampere current passed for one second, then it is called as quantity of electricity.

          What is the unit of it?

Ans:16. Coulomb.

Q:17. The resistance of a field coil measures 65 ohm at 30 degree c and 75 ohm at 75 degree c.

          What is the temperature co-efficient of the conductor at 0 degree c?

Ans:17. 0.0038 degree c.

Q:18. Two important conditions can occur in a circuit. They are open circuit and short circuit.

          In an open circuit what is the value of the circuit resistance and the flow of current?

Ans:18. Resistance- infinity ; Current- zero.

Q:19. Ohm's low gives the relationship between voltage, current and resistance in a circuit.

         What is the relation between current and resistance in a circuit at constant voltage?

Ans:19. Inversely proportional.

Q:20. In any closed circuit, at constant temperature the current is directly proportional to the voltage.

          a) Which law states the above statement?
          b) What is the other statement in the same law?

Ans:20. a) Ohm's law
             b) 1/R

Q:21. In a DC series circuit the total  resistance value will be the algebraic sum of all resistances.

          What will be the value of equivalent resistance in parallel circuit?

Ans:21. Rt =1/1/R1+1/R2+1/R3+ 1/Rn

Q:22. A torch battery with an e.m.f of 6v and having negligible resistance supplies a lamp with a
          current of 0.3 A.

          What is the resistance of the lamp?

Ans:22. 20 ohm

Q:23. If one of the resistors in a parallel circuit is removed, what will happen in the total resistance?

Ans:23. Total resistance increases.

Q:24. In which resistor the highest current will flow in the circuit?

Ans:24. 5 ohm.

Q:25. Two indentical values of two resistors are connected in parallel circuit.

          What will be the value of its equivalent resistance?

Ans:25. Half of the resistance value.

Q:26. The location of short circuit can be detected by connecting voltmeter across the element in the circuit.

          What will be reading of voltmeter in the circuit shown?

Ans:26. 0 volt.

Q:27. An open in parallel circuit causes no current flow in the circuit.

        What is the voltage between the point A and Bin this circuit?

Ans:27. Supply voltage.

Q:28. The algebraic sum of the current meeting at a point is zero in a network.

          Which law states the above statement?

Ans:28. Kirchoff's first law or current law.

Q:29.At each junction of current the sum of the incoming current is equal to the sum of the outgoing current.

       What is the name of the law of the above statement?

Ans:29. Kirchoff's first law or current law.

Q:30. Find the value of 'X' shown in the circuit?

Ans:30. 4 ohm.

Q31. Two lampes rated as 200 W, 250 V are connected in (1) series(2)Parallel across 250 V supply.

        how many times the power will be observed by barallel circuit is greater than the series circuit?

Ans:31. 4 Times.

Q:32. The flasher lamp acts as a switch for other lamps connected in series with the circuit.

         What is the current carrying capacity of the flasher shown in the circuit when 3 rows in parallel with
         each row of 150 mA rating?

Ans:32. 450 mA

Q:33. Neon polarity indicator is used to find the polarity of AC and DC.

           While checking a power source with this indicator if both electrodes in the lamp 'glow',What type
           of power source is this?

Ans:33. Ac.

Q:34. The grade of voltages categorised as L.T.M.T,H.T,and E.H.T.

          What is the grade of volatgefor 11,00 V?

Ans:34. V bc=10 V; V bd =20 V

         


       
         

  


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