The resistance of a wire of iron is $10\, ohms$ and temp. coefficient of resistivity is $5 \times {10^{ - 3}}\,^oC$. At $20\,^oC$ it carries $30$ milliamperes of current. Keeping constant potential difference between its ends, the temperature of the wire is raised to $120\,^oC$. The current in milliamperes that flows in the wire is
  • A$20$
  • B$15$
  • C$10$
  • D$40$
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