When a current of 5 mA is passed through galvanometer having a coil of resistance 15 Ω, it shows full scale deflection. The value of the a be resistance to be put in series with the galvanometer to convert it into to voltmeter of range 0-10 V is
To convert the galvanometer to a voltmeter of range 0–10 V, the series resistance
R is given by: R = V/I – Rg
Substituting V = 10V, I = 5 mA and Rg = 15 Ω:
R = 10/0.005 – 15 = 2000 – 15 = 1985 Ω
Answer: (C) 1.985 × 10³ Ω.
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To convert a galvanometer to a voltmeter, the series resistance (R) is calculated as:
V = I(Rg + R)
Where:
V = 10 volts
I = 5 mA = 0.005 A
Rg = 15Ω
10 = 0.005 × (15+R)
15 + R = 10/0.005 = 2000
R = 2000 −15 = 1985Ω
Answer: (C) 1.985 × 10³ Ω
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