The value of R required to make the galvanometer measure voltage up to 40V in the diagram above
- 1885\(\Omega\)
-
1990\(\Omega\)
- 1995\(\Omega\)
- 1100\(\Omega\)
The correct answer is: B
Explanation
To find the value of R required to make the galvanometer measure up to 40 V, we can use the following formula for a series circuit involving a galvanometer
V = I ( R + r )
R = \(\frac{\text{V}}{\text{I}}\) - r
where R = resistance in series = ?, V = total voltage = 40V, I = current through galvanometer = 20Am = 0.02A and r = internal resistance = 10\(\Omega\)
R = \(\frac{40}{0.02}\) - 10
R = 2000 - 10 = 1990\(\Omega\)
There is an explanation video available .