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NEET 2011 (AIPMT, Mains) · Electrical Power & Heating Effect

Electrical Power & Heating Effect question from NEET 2011 (AIPMT, Mains)

Q59NEET 2011 · AIPMT · MAINSMedium

Electrical Power & Heating Effect

A thermocouple of negligible resistance produces an e.m.f. of 40 µV/ºC in the linear range of temperature. A galvanometer of resistance 10 ohm whose sensitivity is 1 µA/division, is employed with the thermocouple. The smallest value of temperature difference that can be detected by the system will be

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Answer: (d)

  1. Smallest detectable current = 1 division =1 μ= 1\ \muA.
  2. Required emf =IR=1 μA×10 Ω=10 μ= IR = 1\ \mu\text{A} \times 10\ \Omega = 10\ \muV.
  3. Δθ=1040=0.25∘\Delta\theta = \frac{10}{40} = 0.25^\circC. So the answer is (d).
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