Q86 / 125 · BITSAT 2021 · Physics

The electric potential $V$ is given as a function of distance $\times($ metre $)$ by $V=\left(5 x^{2}+10 x-4\right)$ volt. Question: Value of electric field at $x=1 \mathrm{~m}$ is

  • A
    $-23 \mathrm{~V} / \mathrm{m}$
  • B
    $11 \mathrm{~V} / \mathrm{m}$
  • C
    $6 \mathrm{~V} / \mathrm{m}$
  • Correct answer
    D
    $-20 \mathrm{~V} / \mathrm{m}$

Solution

$\mathrm{V}=5 x^{2}+10 x-4$ $\mathrm{E}=\frac{-\mathrm{dV}}{\mathrm{dx}}=-(10 x+10)$ At $x=1 m, \mathrm{E}=-20 \mathrm{~V} / m$

Hence, the correct answer is option: 'D'.

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