Question

The wavelength of an electromagnetic wave is measured to be 600 m. What is the frequency of the wave

Answer 1

The speed of the sound wave will be

v = wavelength x frequency

or

v = λ x f

here,

λ = 35cm = 0.35m

f = 2kHz = 2000 Hz

thus,

v = 0.35 x 2000 = 700 m/s

now, time taken by it to travel 1.5km (=1500 m) will be

t = velocity / distance = 700/1500

thus,

t = 0.467 seconds

Answer 2

The frequency of the wave is $5X10^{5}$ Hertz.

Given,

Wavelength of the wave=600 m.

To find,

the frequency of the wave.

Solution:

The energy of an electromagnetic wave can be calculated as:

(a)$E=\frac{hc}{λ}$

where,

E-energy of the wave

h-Plank's constant

$h=6.626X10^{-34} J sec$

λ-wavelength of the wave

c-speed of light

$c=3X10^{8} \frac{m}{s}$.

Also,

(b)$E=hf$

where,

E-energy of the wave

h-Plank's constant

f-frequency of the wave.

(a)=(b)

$\frac{hc}{λ}=hf\\f=\frac{hc}{hλ} \\f=\frac{c}{λ} \\f=\frac{3X10^{8} }{600} \\f=0.5X10^{6} Hertz\\f=5X10^{5} Hertz.$

The wave has a frequency of $5X10^{5}$ Hertz.

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