Bissoy.com
Doctors Medicines MCQs Q&A

A galvanometer coil has a resistance of 50 Ω and the meter shows full scale deflection for a current of 5 mA. This galvanometer is converted into voltmeter of range 0 – 20 V by connecting

A galvanometer coil has a resistance of 50 Ω and the meter shows full scale deflection for a current of 5 mA. This galvanometer is converted into voltmeter of range 0 – 20 V by connecting Correct Answer 3950 Ω in series with galvanometer

CONCEPT:

  • An instrument used to detect, measure, and determine the direction of electric currents is called galvanometer.
  • A resistance of high value is connected in series to convert the galvanometer into voltmeter.

CALCULATION:

[ alt="F1 J.K 16.4.20 Pallavi D18" src="//storage.googleapis.com/tb-img/production/20/04/F1_J.K_16.4.20_Pallavi_D18.png" style="width: 242px; height: 76px;">

Given that:

Current (I) = 5 mA = 5 × 10-3 A

Resistance of galvanometer (RG) = 50 Ω

Let resistance of R Ω is connected in series.

Potential (VAB) = 20 V = 5 × 10-3 × (50 + R)

50 + R = 20/(5 × 10-3) = 4000

Resistance (R) = 4000 – 50 = 3950 Ω

  • Thus 3950 Ω are connected in series with the galvanometer to convert into voltmeter. Hence option 1 is correct.

Related Questions

The figure below shows a circuit for an AC voltmeter. It utilizes a moving-coil meter that gives a full-scale reading when the average current flowing through it is 1 mA. The moving-coil meter has a 50-Ω resistance. The value of R that results in the meter indicating a full-scale reading when the input sine-wave voltage VI is 20 V peak-to-peak is
A galvanometer coil has a resistance of 14 Ω and the metre shows full scale deflection for a current of 4 mA. How will you convert the metre into a voltmeter of range 0 to 16 V?
A resistance R is measured using the connection shown in the below figure. The current measured is 10 A on ranges 100A and the voltage measured is 125 V on 150 V range. The scales of the ammeter and voltmeter are uniform. The total number of scale divisions of the ammeter is 100 and that of the voltmeter is 150. The scale division can be distinguished. The constructional error of the ammeter is ± 0.3% and that of voltmeter±0.4%. The resistance of the ammeter is 0.25 Ω. The possible error in the measurement of R is?
A galvanometer having a coil resistance of 60 9 shows full-scale deflection when a current of 1.0 amp passes through it. It can be converted into an ammeter to read currents up to 5.0 amp by:
When an electric current coil of a wattmeter is connected to the electric current path R and the voltage coil is connected between the electric current R path and the neutral side of the balanced three phase supply, it shows 10 kW. The line voltage along the phase sequence RYB is 400 V. The current drawn by the current path is 54 A. What is the new reading of the wattmeter if the voltage coil is connected between the lines B and the Y paths, even if the electric current coil is continuously present in the line R?
A moving coil instrument has a resistance of 70 Ω and gives full scale deflection of 100 scale divisions for a current of 1 mA. The instrument is connected in parallel with a shunt of 30 Ω resistance and this combination is then connected in series with a load and supply. Determine the current in the load when the instrument gives an indication of 80 scale divisions.
The full-scale deflection current of a meter is 4 mA and its internal resistance is 400Ω. This meter is to have full deflection when 400 V is measured. What is the value of the series resistor to be used?
A galvanometer whose resistance is 50 Ω has 25 divisions in it. When a current of 4 × 10-4A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should be connected to a resistance of
The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100 ohms. If this meter is to have full deflection at 5A, what is the value of the shunt resistance to be used?
A permanent magnet moving coil ammeter has a coil resistance of 99ohm and Full Scale DeflectionFSD. current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is