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JEE Main 2023 (31 Jan, Shift 1) · Electric Flux & Gauss's Law

Electric Flux & Gauss's Law question from JEE Main 2023 (31 Jan, Shift 1)

Q66JEE Main 2023 · 31 JAN · SHIFT 1Medium

Electric Flux & Gauss's Law

Expression for an electric field is given by E⃗=4000x2i^ Vm\vec{E} = 4000x^{2}\hat{i}\ \frac{\text{V}}{\text{m}}. The electric flux through the cube of side 20 cm20\text{ cm} when placed in electric field (as shown in the figure) is __________ V cm\text{V cm}.

Figure

Numerical answer type. Work it out, then open the answer.

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Answer: 640

  1. The cube lies from x=0x = 0 to x=0.2x = 0.2 m; only the faces normal to xx give flux.
  2. At x=0x = 0: E=0E = 0. At x=0.2x = 0.2: E=4000(0.2)2=160E = 4000(0.2)^2 = 160 V/m.
  3. ϕ=160×(0.2)2=6.4\phi = 160\times(0.2)^2 = 6.4 V m =640= 640 V cm.
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