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8.Electromagnetic waves
easy
Light is an electromagnetic wave. Its speed in vacuum is given by the expression
A
$\sqrt {{\mu _o}{\varepsilon _o}} $
B
$\sqrt {\frac{{{\mu _o}}}{{{\varepsilon _o}}}} $
C
$\sqrt {\frac{{{\varepsilon _o}}}{{{\mu _o}}}} $
D
$\frac{1}{{\sqrt {{\mu _o}{\varepsilon _o}} }}$
(AIIMS-2002)
Solution
${\mu _0} = 4\pi \times {10^{ – 7}},\,{\varepsilon _0} = 8.85 \times {10^{ – 12}}\frac{{N{\rm{ – }}{m^2}}}{{{C^2}}}$
so $c = \frac{1}{{\sqrt {{\mu _0}{\varepsilon _0}} }} = 3 \times {10^8}\frac{{meter}}{{sec}}.$
Standard 12
Physics
