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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Physics
Chapter
Experimental Physics

NTA Abhyas 2020 · Physics · Experimental Physics

Two tangent galvanometers A and B have coils of radii 8cm and 16cm...

Two tangent galvanometers AAand BB have coils of radii 8cm8cm and 16cm16cm respectively and resistance 8Ω8Ω each. They are connected in parallel with a cell of emf 4V4V and negligible internal resistance. The deflections produced in the tangent galvanometers A and B are 30°and60°30 ° and60 ° respectively. If A has 22 turns, then the number of turns BB must have isTwo tangent galvanometers A and B have coils of radii 8cm and 16cm respectively and resistance 8Ω each. They are

Correct answer

12

Step-by-step solution

Current in tangent galvanometer

I=2rBHμ0Ntanθ..(i)I = \dfrac{2r{B}_{H}}{{\mu}_{0}N}tan \theta . . \left(i\right)

Two tangent galvanometers A and B have coils of radii 8cm and 16cm respectively and resistance 8Ω each. They are

From Eq. (i), we get

rtanθN=μ0I2BH=same for both\dfrac{rtan \theta}{N} = \dfrac{{\mu}_{0}I}{2{B}_{H}} = \text{same for both}

∴rAtanθANA=rBtanθBNB∴ \dfrac{{r}_{A}tan {\theta}_{A}}{{N}_{A}} = \dfrac{{r}_{B}tan {\theta}_{B}}{{N}_{B}}

⇒8×1(2)3=163NB⇒ \dfrac{8 \times 1}{\left(2\right)\sqrt{3}} = \dfrac{16\sqrt{3}}{{N}_{B}}

∴NB=12turns∴ {N}_{B} = 12turns
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