Answer: The intensity level of sound in the bedroom is 80dB
Explanation:
Intensity of lawn mower at r=1m is 100dB
Beta1= 10dBlog(I1/Io)
100dB= 10dB log(I1/Io)
10^10= I1/Io
I1= Io(10^10)
10^12)×(10^10)= I1
I1=10^-2w/m^2
Intensity of lawn mower at r=20m
I2/I1=(r1/r2)^2 =(1/20)^2
I2= I1(1/400)
I2=2.5×10^-3W_m^2
Intensity of 4 lown mowers at 20m fro. Window
= 10dBlog(4I2/Io)
= 10^-4/10^-12
=80dB
Answer:
J
Explanation:
The daughter moves with greater acceleration backwards because of her weight.
Answer:
the correct answer is D
Explanation:
In this exercise, the vectors are in the same west-east direction, so we can assume that the positive direction is east and perform the algebraic sum.
R = δ + ε
where
δ = 2.0 m
ε = 7.0 m
the positive sign indicates that it is heading east
R = 2.0 + 7.0
R = 9.0 m
the direction is east
the correct answer is D
Answer:
λ = 5.4196 10⁻⁷m, λ = 541.96 nm this is green ligh
Explanation:
The photoelectric effect was explained by Eintein assuming that the light was made up of particles called photons and these collided with the electrons taking them out of the material.
K = h f -Ф
where K is the kinetic energy of the ejected electrons, hf is the energy of the light quanta and fi is the work function of the material.
The speed of light is related to wavelength and frequency
c = λ / f
f = c /λ
we substitute
K = h c / λ - Φ
for the case that they ask us the kinetic energy of the electons is zero (K = 0)
h c / λ = Ф
λ = h c / Ф
we calculate
λ = 6.63 10⁻³⁴ 3 10⁸ / 3.67 10⁻¹⁸
λ = 5.4196 10⁻⁷m
let's take nm
lam = 541.96 nm
this is green light
