An (0 V - 100 V) MC voltmeter with an internal resistance of 2 Ω is used to measure voltage of up to 200 V. The additional resistance to be connected in series with the voltmeter is ________.

The correct answer is option 1): 2 Ω

Concept:

Current through voltmeter

I =\(V_{max}\over R_{in} \)

where 

V_max is the maximum range

R_in  is the internal resistance in Ω

The additional resistance connected in series to increase the max range to Vmax1

R_add = Reff - Rin

R_eff = \(V_{max 1}\over I\)

where I is the current through the circuit

Calculation:

Given

V_max = 100 V

 Vmax1 = 200 V

R_in = 2 Ω

I = \(100 \over 2\)

= 50 A

R_eff = (\(200 \over 50\))

= 4 Ω

The additional resistance needs to be connected is 

R_add = R_eff - R_in

= 4 - 2

= 2 Ω