A coil is placed perpendicular | EMI

JEE MAINS 2024

31.01.24 S1

Question

A coil is placed perpendicular to a magnetic field of 5000" " T. When the field is changed to 3000" " T in 2" " s, an induced emf of 22" " V is produced in the coil. If the diameter of the coil is 0.02" " m, then the number of turns in the coil is :

Select the correct option:

140

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Solution

Sol. $$ \begin{aligned} & \varepsilon=\mathrm{N}\left(\frac{\Delta \phi}{\mathrm{t}}\right) \\ & \Delta \phi=(\Delta \mathrm{B}) \mathrm{A} \\ & \mathrm{~B}_{\mathrm{i}}=5000 \mathrm{~T}, \\ & \mathrm{~B}_{\mathrm{f}}=3000 \mathrm{~T} \\ & \mathrm{~d}=0.02 \mathrm{~m} \\ & \mathrm{r}=0.01 \mathrm{~m} \\ & \Delta \phi=(\Delta \mathrm{B}) \mathrm{A} \\ & =(2000) \pi(0.01)^2=0.2 \pi \\ & \varepsilon=\mathrm{N}\left(\frac{\Delta \phi}{\mathrm{t}}\right) \Rightarrow 22=\mathrm{N}\left(\frac{0.2 \pi}{2}\right) \\ & \mathrm{N}=70 \end{aligned} $$

Question Tags

JEE Main

Physics

Medium

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