In Guericke's experiment to show the effect of atmospheric pressure, two copper hemispheres were tightly fitted to each other to form a hollow sphere and the air from the sphere was pumped out to create vacuum inside. If the radius of each hemisphere is $R$ and the atmospheric pressure is $p$, then the minimum force required (when the two hemispheres are pulled apart by the same force) to separate the hemispheres is
KVPY 2017, Advanced
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(c)

In Guericke's experiment,

If pressure difference between outside and inside is $p$, then

$\frac{F}{A}=p \text { or } F=p A=p \pi R^2$

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