Question

plzzz guys answer it if uh know
25.) A voltmeter with resistance 2500 ohm -indicates a
voltage of 125V in the circuit shown in figure.
What is the series resistance to be connected to
voltmeter so that it indicates 100V? Consider ideal
battery :-

(1) 625 ohm
(2) 120 ohm
(3) 550 ohm
(4) Data are insufficient​

Answer 1

Answer:

THE ANSWER TO THIS QUESTION IS 4) DATA INSUFFICIENT

Explanation:

GIVEN:

PARAMETER               INITIALLY                        FINALLY

VOLTAGE                     125 V                                   100 V

CURRENT                     0.05 A                                 UNKNOWN

RESISTANCE                 2500 Ohm                         2500+x Where x is the                                                                                            

                                                                                  resistance to be added                                  

                                                                                  in   series.

If we assume that the battery is ideal and hence that the current is not UNKNOWN but is the same as in case 1 and batteries capacity is constant that is not at all possible by "OHMS LAW"

                      as V = I×R

If the resistance is in series it increases and becomes 2500+x therefore putting I constant V would increase but not decrease hence second case current should be mentioned .

Only if current is taken same and,

Assuming parallel connection of resistance with volt meter this can be solved as the resultant resistance is less than actual.

Hence proved that the option is d) DATA IS INSUFFICIENT