Answer:
The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.
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Answer:

Explanation:
given,
refractive index of lens, n = 1.70
Radius of curvature of front surface. R₁ = 20 cm
Radius of curvature of the back surface, R₂ = 30 cm
focal length= ?

R₁ = +20 cm
R₂ = -30 cm
n = 1.70




the focal length of the lens is equal to 17.15 cm
Answer:
mechanical waves,
.
the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone.
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If the amplitude increases the volume increases and vice versa.
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The type of medium affects a sound wave as sound travels with the help of the vibration in particles.
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The higher the frequency, the shorter the wavelength.
Explanation:
Compression is above the equilibrium and rarefaction is below