JEE MAIN - Physics (2021 - 24th February Morning Shift - No. 21)
An electromagnetic wave of frequency 5 GHz, is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are 2. Its velocity in this medium is ____________ $$\times$$ 107 m/s.
Odpověď
15
Vysvětlení
Given, $$\mu$$r = $$\varepsilon $$r = 2
where, $$\mu$$r is relative permeability, $$\varepsilon $$r is relative permittivity.
Speed of electromagnetic wave v is given by
$$v = {c \over n}$$
where, n = refractive index = $$\sqrt {{\mu _r}{\varepsilon _r}} = \sqrt 4 = 2$$
$$ \Rightarrow v = {{3 \times {{10}^8}} \over 2}$$ = 15 $$\times$$ 107 m/s
$$\because$$ x $$\times$$ 107 = 15 $$\times$$ 107
$$\Rightarrow$$ x = 15
where, $$\mu$$r is relative permeability, $$\varepsilon $$r is relative permittivity.
Speed of electromagnetic wave v is given by
$$v = {c \over n}$$
where, n = refractive index = $$\sqrt {{\mu _r}{\varepsilon _r}} = \sqrt 4 = 2$$
$$ \Rightarrow v = {{3 \times {{10}^8}} \over 2}$$ = 15 $$\times$$ 107 m/s
$$\because$$ x $$\times$$ 107 = 15 $$\times$$ 107
$$\Rightarrow$$ x = 15