Q. In the circuit shown, the voltage drop across the 15Ω resistor is 30 V having the polarity as indicated. The ratio of potential difference across 5Ω resistor and resistance R is
(a) 2/7
(b) 0.4
(c) 5/7
(d) 1
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Ans: (d)
Sol: Since , Voltage drop across 15 ohm is 30 V . Hence current in 15 ohm resistor is = 30/15 = 2A
Apply KCL at junction B and find the current in Path BC .
Hence , current in path BC = 2+5 = 7 A
Now , Applying KVL in loop we get
2R = 35 v
Hence , The ratio of potential difference across 5Ω resistor and resistance R is
$ \displaystyle \frac{V_{BC}}{V_R} = \frac{35}{35} = 1 $