Question 68: Electromagnetic Induction

Question

A coil is places perpendicular to a magnetic field of $$5000 \mathrm{~T}$$. When the field is changed to $$3000 \mathrm{~T}$$ in $$2 \mathrm{~s}$$, an induced emf of $$22 \mathrm{~V}$$ is produced in the coil. If the diameter of the coil is $$0.02 \mathrm{~m}$$, then the number of turns in the coil is:

Accepted Answer

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

Answer

35

Answer

70

Answer

7

Answer

140

Electromagnetic Induction

A coil is places perpendicular to a magnetic field of $5000 \mathrm{~T}. When the field is changed to 3000 \mathrm{~T} in 2 \mathrm{~s}, an induced emf of 22 \mathrm{~V} is produced in the coil. If the diameter of the coil is 0.02 \mathrm{~m}$, then the number of turns in the coil is:

Choose the correct answer: