Answer:
D. 4000 km
Explanation:
f = Frequency of wave that is being transmitted = 76 Hz
= Wavelength of wave that is being transmitted
v = The velocity of electromagnetic waves through air = 
Velocity of a wave is given by

Hence, the approximate wavelength of the waves is 4000 km
Answer:
Part a)

Part b)

Explanation:
Part a)
Level of sound = 75 dB
now we know that

here we know that

now we have


Part b)
Intensity of sound wave is given as

here we know that

so we have


now we know



now we have


Hot spots are fixed locations in the earth's mantle where heat from the earth's interior rises to the surface and produces volcanism. the earth's plates, which are slowly but constantly moving, are pierced by the uprising magma. as they move away form the hotspot, the volcanoes become dormant and are replaces by new volcanoes. The direction of the line formed from the previous volcanoes indicates the direction :)))
Answer:
The intensity at 10° from the center is 3.06 × 10⁻⁴I₀
Explanation:
The intensity of light I = I₀(sinα/α)² where α = πasinθ/λ
I₀ = maximum intensity of light
a = slit width = 2.0 μm = 2.0 × 10⁻⁶ m
θ = angle at intensity point = 10°
λ = wavelength of light = 650 nm = 650 × 10⁻⁹ m
α = πasinθ/λ
= π(2.0 × 10⁻⁶ m)sin10°/650 × 10⁻⁹ m
= 1.0911/650 × 10³
= 0.001679 × 10³
= 1.679
Now, the intensity I is
I = I₀(sinα/α)²
= I₀(sin1.679/1.679)²
= I₀(0.0293/1.679)²
= 0.0175²I₀
= 0.0003063I₀
= 3.06 × 10⁻⁴I₀
So, the intensity at 10° from the center is 3.06 × 10⁻⁴I₀