A solenoid has a core of a material with relative permeability 400 . The windings of the solenoid are…

A solenoid has a core of a material with relative permeability 400 . The windings of the solenoid are insulated from the core and carry a current of $4 \mathrm{~A}$. If the number of turns is 500 per metre, then the magnetizing field is
  1. $2 \pi \times 10^3 \mathrm{Am}^{-1}$
  2. $1 \times 10^3 \mathrm{Am}^{-1}$
  3. $4 \times 10^3 \mathrm{Am}^{-1}$
  4. None of the above

Solution

$\begin{aligned} & \text { Given, } \mathrm{I}=4 \mathrm{~A}, \mathrm{n}=500 \mathrm{~m}^{-1}, \mu_{\mathrm{r}}=400 \\ & \text { Magnetic intensity, } \mathrm{H}=\mathrm{nI}=500 \times 4 \\ & =2000 \mathrm{Am}^{-1} \\ & \mu_{\mathrm{r}}=1+\chi \text { and } \chi=\left(\mu_{\mathrm{r}}-1\right) \\ & \text { Magnetising field, } \mathrm{M}=\chi \mathrm{H}=\left(\mu_{\mathrm{r}}-1\right) \mathrm{H} \\ & =(400-1) \times 2000=399 \times 2000=7.98 \times 10^5 \mathrm{Am}^{-1}\end{aligned}$

Asked in: AP EAMCET 2023 (15 May Shift 1)

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