Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
Concepts Of Physics MCQ Edition [Volume 2]
Exam
Concepts Of Physics MCQ Edition [Volume 2]
Subject
Physics
Chapter
Thermal and Chemical Effects of Electric Current

Concepts Of Physics MCQ Edition [Volume 2] · Physics · Thermal and Chemical Effects of Electric Current

The junction temperatures of a bismuth–silver thermocouple are kept...

The junction temperatures of a bismuth–silver thermocouple are kept at 0^{}^{{}^{\circ}} C and 0.001^{}^{{}^{\circ}} C. Determine the developed thermo-emf (Seebeck emf). Given for bismuth–silver, a = -46 \times 10^{-6} \text{ V }^{}^{{}^{\circ}} C^{-1} and b = -0.48 \times 10^{-6} \text{ V }^{}^{{}^{\circ}} C^{-2}.

Options

  1. A−2.3×10−8 V-2.3 \times 10^{-8} \text{ V}
  2. B4.6×10−8 V4.6 \times 10^{-8} \text{ V}
  3. C−4.6×10−6 V-4.6 \times 10^{-6} \text{ V}
  4. D−4.6×10−8 V-4.6 \times 10^{-8} \text{ V}

Correct answer

D. −4.6×10−8 V-4.6 \times 10^{-8} \text{ V}

Step-by-step solution

The thermo-emf EE developed in a thermocouple when the cold junction is at 0^{}^{{}^{\circ}} \text{C} and the hot junction is at T^{}^{{}^{\circ}} \text{C} is given by the relation:

E=aT+12bT2E = aT + \dfrac{1}{2}bT^2

Given:
a = -46 \times 10^{-6} \text{ V }^{}^{{}^{\circ}} \textC^{-1}
b = -0.48 \times 10^{-6} \text{ V }^{}^{{}^{\circ}} \textC^{-2}
T = 0.001^{}^{{}^{\circ}} \text{C} = 10^{-3} ^{}^{{}^{\circ}} \text{C}

Substituting the values into the formula:

E=(−46×10−6)(10−3)+12(−0.48×10−6)(10−3)2E = (-46 \times 10^{-6})(10^{-3}) + \dfrac{1}{2}(-0.48 \times 10^{-6})(10^{-3})^2

E=−46×10−9−0.24×10−12E = -46 \times 10^{-9} - 0.24 \times 10^{-12}

Since the second term is negligibly small compared to the first term, it can be ignored:

E≈−46×10−9 VE \approx -46 \times 10^{-9} \text{ V}

E=−4.6×10−8 VE = -4.6 \times 10^{-8} \text{ V}
Practice Thermal and Chemical Effects of Electric Current on Quantrex Academy →

More from Thermal and Chemical Effects of Electric Current

A wire with a resistance of 25 Ω carries an electric current of 2.0 A . Determine the… Concepts Of Physics MCQ Edition [Volume 2]A heater coil has a specification of 250 V , 500 W . Determine the resistance of the… Concepts Of Physics MCQ Edition [Volume 2]A nichrome wire ( ρ = 1.0 × 10^ -6 Ω m ) is used to build a heater coil intended to… Concepts Of Physics MCQ Edition [Volume 2]A heater coil, designed to operate at 500 W across a 250 V supply, is fabricated from a… Concepts Of Physics MCQ Edition [Volume 2]A nichrome wire ( ρ = 1.0 × 10^ -6 Ω m ) with a cross-sectional area of 0.5 mm^2 is used… Concepts Of Physics MCQ Edition [Volume 2]A coil with a resistance of 100 Ω is connected across a battery having an emf of 6.0 V .… Concepts Of Physics MCQ Edition [Volume 2]When connected across a 220 V power supply, an electric bulb consumes 60 W of power. What… Concepts Of Physics MCQ Edition [Volume 2]A bulb with a rating of 250 V , 100 W is connected to a 220 V power supply situated 10 m… Concepts Of Physics MCQ Edition [Volume 2] Full Thermal and Chemical Effects of Electric Current list All Concepts Of Physics MCQ Edition [Volume 2] PYQs