Verified Solution • 2025–26 Session moderate

QAIPMT-2010-Ph-2090: NEET 2010 Physics - Class 12 AIPMT-2010-Ph-2090 Solution: Two positive ions each carrying a charge q are separated by a…

Two positive ions each carrying a charge q are separated by a distance d. If F is the force of repulsion between the ions the number of electrons missing from each ion will be (e being the charge on an electron)

\frac{4\pi\epsilon_0 Fd^2}{e^2}

\sqrt{\frac{4\pi\epsilon_0 Fe^2}{d^2}}

\sqrt{\frac{4\pi\epsilon_0 Fd^2}{e^2}}

\frac{4\pi\epsilon_0 Fd^2}{q^2}

Multiple Choice Options

A $f\,$ f and ${I \over 4}$ 4 I _
B ${{3f} \over 4}$ 4 3 f _ and ${I \over 2}$ 2 I _
C $f$ f and ${{3I} \over 4}$ 4 3 I _
D ${f \over 2}$ 2 f _ and ${I \over 2}$ 2 I _

Step-by-Step Verified Solution

By covering aperture, focal length does not change. But intensity is reduced by 1 4 times, as aperture diameter d 2 is covered. _ I' = I - I 4 = 3 I 4 _ New focal length = f and intensity = 3 I 4

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