Question

A source is emitting waves of frequency 400 Hz and wavelength 0.3 m. How long does it take the wave to travel 300 m?
Options
70 S
60 s
O 12 s
O 2.5​

Answer 1

Answer :

The wave takes 2.5 seconds to travel a distance of 300 m.

Explanation :-

We have :-

→ Frequency of the wave (ν) = 400 Hz

→ Wavelength (λ) = 0.3 m

→ Distance = 300 m

________________________________

Firstly, let's calculate the speed of the wave (υ) .

υ = νλ

⇒ υ = 400 × 0.3

⇒ υ = 120 m/s

Now, we know that :-

Time = Distance/Speed

⇒ Time = 300/120

⇒ Time = 2.5 seconds

Answer 2

Given:-

• A source is emitting waves of frequency 400 Hz and wavelength 0.3 m.

To Find:-

• Time will it take to travel 300 m

Formula Used:-

• ${\boxed{\bf{v =nλ}}}$

• ${\boxed{\bf{Speed(v) =\dfrac{Distance(d)}{Time(t)}}}}$

Here,

• v = Speed of Wave

• n = Frequency of Wave

• λ = Wavelength of Wave

Solution:-

Using Formula,

$\bf :\implies\:v =nλ$

Here,

• n = 400 Hz

• λ = 0.3 m

Putting values,

$\sf :\implies\:v =400\times0.3$

$\bf :\implies\:v =120ms^{-1}$

Now,

$\sf :\implies\:Speed(v) =\dfrac{Distance(d)}{Time(t)}$

$\sf :\implies\: t=\dfrac{d}{v}$

$\sf :\implies\: t=\dfrac{300}{120}$

$\sf :\implies\: t=\dfrac{30}{12}$

$\sf :\implies\: t=\dfrac{5}{2}$

$\bf :\implies\: t=2.5\:sec$

Hence, it will take 2.5sec the wave to travel 300m.

[ Option {4} is correct ]

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