Current Electricity and Electrical InstrumentHard
Question
A D.C. supply of 120 V is connected to a large resistance X. A voltmeter of resistance 10kΩ placed in series in the circuit reads 4V. This is an unusual use of voltmeter for measuring very high resistance. The value of X is :
Options
A.390 kΩ
B.290 kΩ
C.190 kΩ
D.300 kΩ
Solution
I = 
= 4 × 10-4
but 4 × 10-4 =
;
4 × 10-4 x + 4 = 120; x =
× 104; x = 290 kΩ
= 4 × 10-4but 4 × 10-4 =
;4 × 10-4 x + 4 = 120; x =
× 104; x = 290 kΩCreate a free account to view solution
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