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प्रश्न
Write down Coulomb’s law in vector form and mention what each term represents.
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उत्तर
The force on the point charge q2 exerted by another point charge q1
`vec"F"_21 = ("K""q"_1"q"_2)/"r"^2 hat"r"_12`
where `hat"r"_2` is the unit vector directed from charge q1 to charge q2, and ‘K’ is the proportionality constant K = `1/(4 pi ε_0)`; ε0 is the permittivity of free space.
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संबंधित प्रश्न
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F = `(Qq)/r^2 hatr`
where the distance r is measured in cm (= 10–2 m), F in dynes (= 10–5 N) and the charges in electrostatic units (es units), where 1 es unit of charge = `1/([3]) xx 10^-9 C`
The number [3] actually arises from the speed of light in vaccum which is now taken to be exactly given by c = 2.99792458 × 108 m/s. An approximate value of c then is c = [3] × 108 m/s.
(i) Show that the coloumb law in cgs units yields
1 esu of charge = 1 (dyne)1/2 cm.
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or, `1/(4pi ∈_0) = (2.99792458)^2 xx 10^9 (Nm^2)/C^2` (exactly).
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