A 228 resistor and a 586 resistor are connected in series ac

A 228 resistor and a 586 resistor are connected in series across a 90.0V line.

A voltmeter connected across the 228 resistor reads 24.0 V . Find the voltmeter resistance.

Find the reading of the same voltmeter if it is connected across the 586 resistor.

PD across 228 ohm is 24 V.

then PD across 586 is 90- 24 = 66 volt.

current through battery and 586 ohm resistor = 66 /586 = 0.113 A

current through 228 ohm resistor = 24/228 = 0.105 A

so current through voltmeter = 0.113 - 0.105 = 7.74 x 10^-3 A

for voltmeter using, V = IR

24 = (7.74 x 10^-3) R

R = 3102.04 ohm .............Ans

now it is connected in parallel connection with 586 ohm.

their equivalent is R\' then

1/R\' = 1/586 + 1/3102.04

R\' = 492.88 ohm

total resistance of circuit = 492.88 + 228 = 720.89 ohm

current through battery = 90 / 720.89 = 0.125

current through 228 ohm = 0.125 A

so reading of voltmeter = 90 - (0.125 x 228) = 61.54 V ......Ans