The electric field in a region is given by vecmathrmE = (2hatmathrmi + 4hatmathrmj + 6hatmathrmk) times 10^3mathrmN / mathrmC . The flux of the field through a rectangular surface parallel to x-z plane is 6.0mathrmNm^2mathrmC^-1 . The area of the surface is __________ mathrmcm^2 . [cite: 195, 196]

Numerical Answer Type:
Enter a numerical value Answer: 15 to 15 +4 marks

Solution & Explanation

### Related Formula phi = vecE cdot vecA [cite: 827] ### Core Logic A surface aligned parallel to the xtext-z plane possesses an area vector pointing completely orthogonal to it along the y-axis direction, meaning vecA = Ahatj[cite: 196, 827]. Performing the dot product: [cite: 827] phi = left[(2hati + 4hatj + 6hatk) times 10^3right] cdot (Ahatj) = 4 times 10^3 A [cite: 195, 827] Given that the net flux magnitude is 6.0\ textNm^2textC^-1 [cite: 196]: 6 = 4 times 10^3 A implies A = frac64 times 10^3 = 1.5 times 10^-3\ textm^2 [cite: 828, 829] Converting square meters to square centimeters (1\ textm^2 = 10^4\ textcm^2): [cite: 196, 830] A = 1.5 times 10^-3 times 10^4 = 15\ textcm^2 [cite: 830] ### Pattern Recognition Always focus exclusively on the specific field component matched to the surface orientation normal[cite: 827]. For an xtext-z plane match, only the hatj coefficient creates flux[cite: 196, 827]. Do not miss the metric scale unit transition at the end (m^2 rightarrow cm^2)[cite: 196, 830]. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics

Reference Study Guides

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Q42 jee_main_2024_31_jan_morning Electric Field Zero Point
Two charges q and 3q are separated by a distance 'r' in air. At a distance x from charge q, the resultant electric field is zero. The value of x is :
  • A. frac(1 + sqrt3)r
  • B. fracr3(1 + sqrt3)
  • C. fracr(1 + sqrt3)
  • D. r(1 + sqrt3)

Solution

### Related Formula E = frackqx^2 ### Core Logic
Electric Field Zero Point diagram for Q42 - JEE Main 2024 Morning
Electric Field Zero Point diagram for Q42 - JEE Main 2024 Morning
For the net electric field to be zero at point P situated at distance x from charge q, the electric fields produced by both charges must be equal in magnitude and opposite in direction. Let the charges be placed at ends of a line. Point P is between them since both charges are of the same sign. (vecE_textnet)_P = 0 frackqx^2 = frack(3q)(r-x)^2 ### Step 2: Solving for x Taking square roots on both sides: frac1x = fracsqrt3r-x r - x = sqrt3x r = x(sqrt3 + 1) x = fracrsqrt3 + 1 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics
Q52 jee_main_2024_31_jan_morning Capacitance With Dielectric
A parallel plate capacitor with plate separation 5 mathrm~mm is charged up by a battery. It is found that on introducing a dielectric sheet of thickness 2 mathrm~mm, while keeping the battery connections intact, the capacitor draws 25 \% more charge from the battery than before. The dielectric constant of the sheet is _____.
Numerical Answer. Answer: 2 to 2

Solution

### Related Formula C = fracvarepsilon_0 Ad C' = fracvarepsilon_0 Ad - t + fractK Q = CV ### Core Logic Initially, the charge stored without the dielectric is: Q_i = fracA varepsilon_0d V After introducing a dielectric of thickness t, the new capacitance C' leads to a new charge Q_f: Q_f = fracA varepsilon_0 Vd - t + fractK ### Step 2: Charge Relationship Given that the capacitor draws 25\% more charge: Q_f = 1.25 Q_i = frac54 Q_i Equating the expressions: fracA varepsilon_0 Vd - t + fractK = 1.25 left( fracA varepsilon_0 Vd right) frac15 - 2 + frac2K = frac1.255 frac13 + frac2K = frac1.255 = frac14 3 + frac2K = 4 frac2K = 1 Rightarrow K = 2 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Electrostatics

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