<u>Answer:</u>
<em>When red light enters the lens its wavelength decreases but its frequency remains the same.
</em>
<u>Explanation:</u>
Lens is made of glass which is a <em>denser medium</em> when compared with air. Thus light will undergo refraction and bend toward the normal. On entering a denser medium from rarer medium the speed of light decreases.
<em>Speed, frequency and wavelength of an electromagnetic wave</em> are related according to the equation.
<em> v=ϑλ
</em>
Where is <em>v is the frequency, λ is the wavelength and v is the speed of the em wave.
</em>
On entering the lens the wavelength of the red light as well as speed decreases but the<em> frequency remains the same.
</em>
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The answer is already in the blank for, its was greater
b. 460.8 m/s
Explanation:
The relationship between the speed of the wave along the string, the length of the string and the frequency of the note is

where v is the speed of the wave, L is the length of the string and f is the frequency. Re-arranging the equation and substituting the data of the problem (L=0.90 m and f=256 Hz), we can find v:

c. 18,000 m
Explanation:
The relationship between speed of the wave, distance travelled and time taken is

where
v = 6,000 m/s is the speed of the wave
d = ? is the distance travelled
t = 3 s is the time taken
Re-arranging the formula and substituting the numbers into it, we find:

Answer:
from someone watching the bulldozer from the cab of the truck or from elsewhere on the flatbed.
Explanation: