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1. Electric charges and fields — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics1. Electric charges and fields1 Mark
MCQ
An electric field converges at the origin whose magnitude is given by the expression $E = 100\,r\,Nt/Coul$, where $r$ is the distance measured from the origin.
  • A
    total charge contained in any spherical volume with its centre at origin is negative.
  • B
    total charge contained at any spherical volume, irrespective of the location of its centre, is negative.
  • C
    total charge contained in a spherical volume of radius $3\, \,cm$ with its centre at origin has magnitude $3 \times 10^{-13}\ C.$
  • ✓
    all of the above
✓

Answer

Correct option: D.
all of the above
d
As the electric field converges at the origin so total charge contained in any spherical volume, irrespective of the location, is negative.

By Gauss theorem $\int \vec{E} \cdot d \vec{s}=\frac{q}{\in_{0}}$

We have $-E\left(4 \pi r^{2}\right)=\frac{q}{\in_{0}} \Rightarrow q=-3 \times 10^{-13} C$

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Column $I$ shows four situations of standard Young's double slit arrangement with the screen placed far away from the slits $S_1$ and $S_2$. In each of these cases $\mathrm{S}_1 \mathrm{P}_0=\mathrm{S}_2 \mathrm{P}_0, \mathrm{~S}_1 \mathrm{P}_1-\mathrm{S}_2 \mathrm{P}_1=\lambda / 4$ and $\mathrm{S}_1 \mathrm{P}_2-\mathrm{S}_2 \mathrm{P}_2=\lambda / 3$, where $\lambda$ is the wavelength of the light used. In the cases $\mathrm{B}, \mathrm{C}$ and $\mathrm{D}$, a transparent sheet of refractive index $\mu$ and thickness $t$ is pasted on slit $\mathrm{S}_2$. The thicknesses of the sheets are different in different cases. The phase difference between the light waves reaching a point $\mathrm{P}$ on the screen from the two slits is denoted by $\delta(\mathrm{P})$ and the intensity by $I(\mathrm{P})$. Match each situation given in Column $I$ with the statement$(s)$ in Column $II$ valid for that situation.

Column $I$ Column $II$
$(A)$ $Image$ $(p)$ $\delta\left(\mathrm{P}_0\right)=0$
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