Electrostatics & Capacitors · JEE Main previous year questions

2019 38 questions

1. Q362019 · 12 Jan 2019 · Shift 1

   A light wave is incident normally on a glass slab of refractive index 1.5. If 4 % of light gets reflected and the amplitude of the electric field of the incident light is 30 V/m, then the amplitude of the electric field for the wave propagating in the glass medium will be :

   1. A.6 V/m
   2. B.10 V/m
   3. C.30 V/m
   4. D.24 V/m
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   Answer: D

2. Q372019 · 12 Jan 2019 · Shift 1
   
   1. A.$2ql\hat{j}$
   2. B.$(ql)\frac{\hat{i}+\hat{j}}{\sqrt{2}}$
   3. C.$\sqrt{3}ql\frac{\hat{j}-\hat{i}}{\sqrt{2}}$
   4. D.$-\sqrt{3}ql\hat{j}$
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   Answer: D

3. Q472019 · 12 Jan 2019 · Shift 1
   
   1. A.$\frac{1}{8}\frac{Q^2}{C}$
   2. B.$\frac{5}{8}\frac{Q^2}{C}$
   3. C.$\frac{3}{4}\frac{Q^2}{C}$
   4. D.$\frac{3}{8}\frac{Q^2}{C}$
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   Answer: D

4. Q522019 · 12 Jan 2019 · Shift 1
   
   1. A.
   2. B.
   3. C.
   4. D.
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   Answer: B

5. Q442019 · 12 Jan 2019 · Shift 2

   A parallel plate capacitor with plates of area $1{\mathrm{m}}^2$ each, are at a separation of 0.1 m. If the electric field between the plates is 100 N/C, the magnitude of charge on each plate is : (Take ${\epsilon }_0=8.85\times 10^{-12}\frac{C^2}{N\cdot m^2}$)

   1. A.$9.85\times 10^{-10}\mathrm{C}$
   2. B.$8.85\times 10^{-10}\mathrm{C}$
   3. C.$6.85\times 10^{-10}\mathrm{C}$
   4. D.$7.85\times 10^{-10}\mathrm{C}$
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   Answer: B

6. Q492019 · 12 Jan 2019 · Shift 2
   
   1. A.$\frac{6}{5}\mu F$
   2. B.$\frac{7}{11}\mu F$
   3. C.$4\mu \mathrm{F}$
   4. D.$\frac{7}{10}\mu F$
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   Answer: B

7. Q532019 · 12 Jan 2019 · Shift 2
   
   1. A.zero
   2. B.$1.5\mu \mathrm{A}$
   3. C.$2\mu \mathrm{A}$
   4. D.$3\mu \mathrm{A}$
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   Answer: A

8. Q332019 · 11 Jan 2019 · Shift 2

   An electric field of $1000\text{ V/m}$ is applied to an electric dipole at angle of $45^{\circ }$. The value of electric dipole moment is $10^{-29}\text{ C.m}$. What is the potential energy of the electric dipole?

   1. A.$-7\times 10^{-27}\text{ J}$
   2. B.$-9\times 10^{-20}\text{ J}$
   3. C.$-10\times 10^{-29}\text{ J}$
   4. D.$-20\times 10^{-18}\text{ J}$
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   Answer: A

9. Q402019 · 11 Jan 2019 · Shift 2

   A paramagnetic substance in the form of a cube with sides $1\text{ cm}$ has a magnetic dipole moment of $20\times 10^{-6}\text{ J/T}$ when a magnetic intensity of $60\times 10^3\text{ A/m}$ is applied. Its magnetic susceptibility is

   1. A.$3.3\times 10^{-4}$
   2. B.$2.3\times 10^{-2}$
   3. C.$4.3\times 10^{-2}$
   4. D.$3.3\times 10^{-2}$
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   Answer: A

10. Q432019 · 11 Jan 2019 · Shift 2

    A $27\text{ mW}$ laser beam has a cross-sectional area of $10{\text{ mm}}^2$. The magnitude of the maximum electric field in this electromagnetic wave is given by : [Given permittivity of space ${ϵ}_0=9\times 10^{-12}\text{ SI units}$, Speed of light $c=3\times 10^8\text{ m/s}$]

    1. A.$2\text{ kV/m}$
    2. B.$1\text{ kV/m}$
    3. C.$1.4\text{ kV/m}$
    4. D.$0.7\text{ kV/m}$
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    Answer: C

11. Q542019 · 11 Jan 2019 · Shift 2
    
    1. A.
    2. B.
    3. C.
    4. D.
    Show answer

    Answer: A

12. Q422019 · 9 Jan 2019 · Shift 1

    For a uniformly charged ring of radius R, the electric field on its axis has the largest magnitude at a distance h from its center. Then value of h is :

    1. A.$\frac{R}{\sqrt{5}}$
    2. B.$\frac{R}{\sqrt{2}}$
    3. C.R
    4. D.$R\sqrt{2}$
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    Answer: B

13. Q552019 · 9 Jan 2019 · Shift 1
    
    1. A.$\frac{K{ϵ}_0{a}^2}{2d(K+1)}$
    2. B.$\frac{K{ϵ}_0{a}^2}{d(K-1)}\ln K$
    3. C.$\frac{K{ϵ}_0{a}^2}{d}\ln K$
    4. D.$\frac{1}{2}\frac{K{ϵ}_0{a}^2}{d}$
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    Answer: B