Electrostatics Question 284
Question: A fully charged capacitor has a capacitance ?C. It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity s and mass ?m. If the temperature of the block is raised by ?$ \Delta T $ ?, the potential difference v across the capacitance is [AIEEE 2005]
Options:
A) $ 4kV $
B) $ 6kV $
C) $ 8kV $
D) $ 10kV $
Show Answer
Answer:
Correct Answer: C
Solution:
As $ Q=CV,{{( {Q _{\text{1}}} )} _{\text{max}}}=\text{1}{{0}^{\text{6}}}\times \text{6}\times \text{1}{{0}^{\text{3}}}=\text{ 6}mC $
While $ {{( {Q _{\text{2}}} )} _{\text{max}}}=\text{3}\times \text{1}{{0}^{\text{6}}}\times \text{4}\times \text{1}{{0}^{\text{3}}}=\text{12}\mu C $
However in series charge is same so maximum charge on C2 will also be 6 mC (and not 12 mC) and potential difference across it $ {V _{\text{2}}}=\text{ 6}\mu C/\text{3}\mu F=\text{2}KV $ and as in series $ V={V _{\text{1}}}+{V _{\text{2}}} $ so $ {V _{\text{max}}}=\text{ 6}KV+\text{ 2}KV=\text{ 8}KV $
