In the Circuit Shown Below, There Will Be a Non-zero Reading in Galvanometer G ..

To Catechumen the Given Galvanometer (of Known Resistance and Figure of Merit) into an Ammeter of Desired Range and to Verify the same

Aim
To convert the given galvanometer (of known resistance and figure of merit) into an ammeter of desired range and to verify the aforementioned.

Apparatus
A weston blazon galvanometer, an ammeter of 0-3 A. range a battery of two cells or battery eliminator, two (10,000 Ω and 200 Ω) resistance boxes, two one way keys, a rheostat, connecting wires and a slice of sand paper.

Theory

Circuit diagram

Procedure

1. Count the full number of divisions on either side of zero of the galvanometer scale. Let it be north.
2. Calculate the electric current (I_g) for full scale deflection i.e., I_g = nk.
3. Calculate the value of shunt resistance, for conversion into ammeter, using the formula,
   
   where I is the range of conversion.
   (The value of shunt resistance S is normally very minor and a resistance box of that range is not available. Such small resistances are obtained by taking wires of copper, constantan, manganin, eureka, etc., of a suitable diameter and length).
4. Cutting a length of the wire 2 cm more the calculated value l. Mark two points on the wire, 1 cm away from each end. Connect this wire to the two terminals of the galvanometer such that the marked points are only exterior the last screws. This galvanometer with shunt wire, will at present piece of work equally an ammeter of range I.
5. Make the electric connections as shown in circuit diagram.
6. Insert the key and adjust the rheostat and then that the galvanometer shows nearly maxi-mum deflection.
7. Notation the reading on the galvanometer scale and as well corresponding reading on the ammeter.
8. Record your observations.

Calculations

Verification

Outcome
As the difference in actual and measured value of currents (as recored, in column 4) is very modest, the conversion is perfect.

Precautions
Same as given in Experiment 8.

Viva Voce

Galvanometer

Question. ane. What is a galvanometer?
Answer. It is a device (instrument) used for detecting feeble electric currents in circuits.

Question. 2. What type of galvanometer is available in laboratories?
Respond. The laboratory galvanometer is a Weston Galvanometer. It has a pivoted coil.

Question.iii. Why the calibration of galvanometer has zero in the eye?
Reply. A needle at zero in the middle can deflect on both sides.

Question.4. Practise we have positive and negative final in a galvanometer?
Respond. No, a galvanometer has no positive and negative terminals. The pointer tin can deflect on either side from naught in the middle.

Question. v. Why the divisions of a galvanometer calibration are as spaced?
Answer. Deflection in pointer is proportional to the current passed. The number of divisions in deflection volition exist proportional to the current passed. I ∝= ∅.

Question. 6. Define figure of merit of a galvanometer.
Answer. The quantity of current required to produce a deflection of ane division in the galvanometer, is called figure of merit of the galvanometer. It is represented by the symbol grand. Its unit of measurement is ampere per division.

Question. 7. Define current sensitivity of a galvanometer.
Answer. The deflection produced in the galvanometer when a unit of measurement electric current is passed through it, is called current sensitivity of the galvanometer.

Question.eight.How are 'effigy of merit' and 'current sensitivity' related to each other?
Respond. They sire reciprocal, Southward₁∝ one/k

Question. 9. Why is the galvanometer chosen a moving ringlet galvanometer?
Reply.Considering in this galvanometer, the coil moves (deflects), while the magnet remains fixed.

Question. ten. Is there whatever moving magnet galvanometer?
Answer. Yes, the tangent galvanometer is called a moving magnet galvanometer.

Question. eleven. Why is tangent galvanometer, called a moving magnet galvanometer?
Answer. Because in tangent galvanometer, the magnet (a small pivoted magnetic needle) moves (deflects), while the coil remains fixed.

Resistance of a galvanometer

Question. 12. What do yous mean past resistance of a galvanometer?
Answer. The resistance of the coil of a galvanometer, is called the resistance of the galvanometer. It is represented by the symbol G.

Question. 13. How practise you determine the resistance of a galvanometer?
Reply. The resistance of a galvanometer is determined by half-deflection method.

Question.14. Why is this method called one-half deflection method?
Answer. Information technology is then because the deflection is made half by using a shunt resistance Due south.

Question. xv. Under what conditions, G = S?
Answer. Chiliad = S, only when series resistance R is very high.

Ammeter

Question. 16. What is an ammeter?
Reply. An ammeter is a device (instrument) for measuring large electric currents in circuits.

Question.17. How is an ammeter used in a circuit?
Answer. An ammeter is used in series in a circuit.

Question.18. Why is an ammeter used in serial in a excursion?
Respond. The whole current to be measured is passed through information technology.

Question.19. What are the required properties of an ammeter?
Respond. An ammeter must accept a very small resistance (zero, if possible) and a large electric current carrying capacity.

Question.20. Why should an ammeter accept a very small resistance?
Reply. So that when put in series in circuit, it should non reduce much the original current to be measured.

Question. 21. Why should an ammeter have a large electric current conveying chapters?
Answer. And so that it may measure big currents.

Voltmeter

Question.22.What is a voltmeter?
Answer.A voltmeter is a device (instrument) for measuring electrical potential difference betwixt two points in a circuit.

Question.23.How is a voltmeter used in a excursion?
Answer.A voltmeter is used in parallel with that branch of excursion at the ends of which the potential difference is to be measured.

Question.24.Why is a voltmeter used in parallel in a circuit?
Answer.The potential difference to be measured is maintained at the terminals of the voltmeter.

Question.25.What are the required properties of a voltmeter?
Respond.A voltmeter must take a very large resistance (infinite, if possible) and a very modest electric current carrying capacity.

Question.26.Why should a voltmeter take a very big resistance?
Answer.So that when put in parallel in circuit, it should non divert much current from parallel branch.

Question.27.Why should a voltmeter have a very minor current carrying chapters?
Reply.So that information technology may not withdraw much current from parallel branch of the circuit.

Conversion of a galvanometer into an ammeter

Question.28.Why is a galvanometer not suitable to work as ammeter?
Answer.A galvanometer has more resistance and less current current-carrying capacity from those required by an ammeter. It will damage when big current catamenia through it.

Question.29.How is a galvanometer converted into an ammeter?
Answer.A galvanometer is converted into an ammeter by connecting a depression resistance in parallel with the galvanometer coil (this parallel low resistance is called shunt).

Question.xxx.How the depression resistance is parallel (shunt) gives required backdrop to the galvanometer?
Answer.The shunt reduces the overall resistance of the ammeter (converted galvanometer) and increases its current-conveying capacity.

Question.31.What is the order of resistance of an ammeter?
Answer.The ammeter resistance is almost equal to the shunt resistance.

Question.32.What exercise you understand by range of an ammeter?
Answer.It is the maximum value of the current which an ammeter can measure out.

Question.33.Which has lesser resistance—a 1 ampere range ammeter or a 10 ampere range ammeter?
Answer.College the range, lower the resistance. A 10 A ammeter has lesser resistance.

Question.34.What is a milli-ammeter?
Answer.It is an ammeter which measures electric current in milli amperes (mA = x^-iii A).

Question.35.What is a micro-ammeter?
Answer.It is an ammeter which measures current in micro amperes (μA = 10^{-half dozen} A).

Question.36.What is full name of an ammeter?
Answer.Total name of an ammeter is ampere-meter.

Question.37.Can nosotros increase/decrease the range of an ammeter?
Answer.We can increase the range but cannot decrease the range of ammeter because for I < I_grand, the value of shunt resistance becomes negative which cannot be possible.

Question.38.What happens when an ammeter is placed in parallel with the circuit?
Answer.Information technology cannot measure out the current in circuit because it only measures the, current which is passing through it.

Conversion of a galvanometer into a voltmeter

Question.39. Why is a galvanometer not suitable to work as voltmeter?
Answer. A galvanometer has less resistance and more electric current-carrying capacity from those required by a voltmeter.

Question. 40. How is a galvanometer converted into a voltmeter?
Answer. A galvanometer is converted into a voltmeter by connecting a high resistance in series with the galvanometer gyre.

Question. 41. How the high resistance in series gives required backdrop to the galvanometer?
Respond. The series high resistance increases the overall resistance of the voltmeter (converted galvanometer) and decreases its current-carrying capacity.

Question. 42. What is the order of resistance of a voltmeter?
Answer. The voltmeter resistance is of the order of series high resistance (R is in x thousands, G is in hundreds).

Question.43. What do you lot understand past the range of a voltmeter?
Answer. Information technology is the maximum value of the potential difference which the voltmeter can mensurate.

Question.44. Which has more resistance—a i volt range voltmeter or a 10 volt range voltmeter?
Answer. Higher the range, higher the resistance. A ten 5 voltmeter has higher resistance.

Question.45. What is a milli-voltmeter?
Answer. Information technology is a voltmeter which measures potential difference in milli-volts (mV = 10^-3 5).

Question. 46. What is a micro-voltmeter?
Answer. It is a voltmeter which measures potential deviation in micro-volts (μV = x^-3 V).

Question.47. Does ordinary voltmeter take infinite resistance?
Answer. No.

Question.48. Proper noun a voltmeter which has infinite resistance.
Answer. Electrostatic voltmeter has infinite resistance. Information technology is also called electrometer. An electronic voltmeter, called Vacuum Tube Volt Meter (VTVM), has well-nigh infinite resistance. It makes an accurate measurement of potential divergence. The potentiometer, at nothing point, also acts as an ideal voltmeter (infinite resistance).

Question.49. Can we increase/subtract the range of a voltmeter?
Reply. Yeah. The range of voltmeter tin be increased by connecting a suitable high resistance in series and can exist decreased a suitable resistance in parallel.

Question. l. What happens when a voltmeter connected in series in a circuit?
Answer. The voltmeter cannot measure the actual p.d. in the circuit considering overall resistance of excursion increases.

Question. 51. What is shunt? State its Due south.fifty. unit of measurement.
Answer. A pocket-size resistance connected in parallel with a galvanometer is chosen shunt. Its S.50. unit of measurement is Olim.

Question. 52. Can moving roll galvanometer be used to discover an a.c. in a circuit? Give reason.
Answer. Information technology cannot be used to detect a.c. in a excursion since it measures the boilerplate value of electric current which is zero over a cycle.

Question. 53. Is the working of MCG affected by the earth magnetic field?
Respond. No. The earth magnetic field is very weak as compared to potent radial magnetic field.

Question. 54. Which has more resistance (a) Ammeter or voltmeter (b) milliammeter or ammeter (c) milli voltmeter or voltmeter.
Reply. (a) voltmeter, (b) milliammeter, (c) voltmeter.

Question. 55. What practise y'all mean by the resistance of a galvanometer?
Respond. The resistance offered by the coil of galvanometer to the flow of current through it is known equally resistance (1000) of the galvanometer.

Physics Lab ManualNCERT Solutions Class 12 Physics Sample Papers

mackeyseellive.blogspot.com

Source: https://www.learncbse.in/to-convert-the-given-galvanometer-of-known-resistance-and-figure-of-merit-into-an-ammeter-of-desired-range-and-to-verify-the-same/

Share this post