Electrostatics & Capacitors · JEE Main previous year questions

2014 3 questions

1. Q462014 · 6 Apr 2014 · Shift 1

   Assume that an electric field $\vec{E}=30x^2\hat{i}$ exists in space. Then the potential difference $V_A-V_O$, where $V_O$ is the potential at the origin and $V_A$ the potential at $x=2\mathrm{m}$ is :

   1. A.$120J/C$
   2. B.$-120J/C$
   3. C.$-80J/C$
   4. D.$80J/C$
   Show answer

   Answer: C

2. Q472014 · 6 Apr 2014 · Shift 1

   A parallel plate capacitor is made of two circular plates separated by a distance $5\mathrm{mm}$ and with a dielectric of dielectric constant $2.2$ between them. When the electric field in the dielectric is $3\times 10^{4}V/m$ the charge density of the positive plate will be close to:

   1. A.$6\times 10^{-7}C/{\mathrm{m}}^2$
   2. B.$3\times 10^{-7}C/{\mathrm{m}}^2$
   3. C.$3\times 10^{4}C/{\mathrm{m}}^2$
   4. D.$6\times 10^{4}C/{\mathrm{m}}^2$
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   Answer: A

3. Q482014 · 6 Apr 2014 · Shift 1

   In a large building, there are 15 bulbs of $40\mathrm{W}$, 5 bulbs of $100\mathrm{W}$, 5 fans of $80\mathrm{W}$ and 1 heater of $1\mathrm{kW}$. The voltage of electric mains is $220\mathrm{V}$. The minimum capacity of the main fuse of the building will be:

   1. A.$8\mathrm{A}$
   2. B.$10\mathrm{A}$
   3. C.$12\mathrm{A}$
   4. D.$14\mathrm{A}$
   Show answer

   Answer: C