MHT CET Medical202624 April 2026Evening ShiftPhysicsCurrent ElectricityActual
The range of voltmeter is 10 V and its resistance is 50 . To convert it to a voltmeter of range 15 V , how much resistance is to be added?
Options
- A25 resistor in parallel.
- B25 resistor in series.
- C125 resistor in parallel.
- D125 resistor in series.
Correct answer
B. 25 resistor in series.
Step-by-step solution
Current for full scale deflection of the voltmeter is given by I_g = V₁ R_v . Substituting the given values, I_g = 10 50 = 0.2 A . To increase the range of the voltmeter to V₂ = 15 V , a resistance R must be connected in series with it. The new range is given by V₂ = I_g(R_v + R) . Substituting the values, 15 = 0.2(50 + R) . 50 + R = 15 0.2 = 75 R = 75 - 50 = 25 . Thus, a 25 resistor must be connected in series. Answer: 25 resistor in series.