Headphones, refrigerator magnets, and compasses
Hope that was helpful.
Answer:
λ = 2.7608 x 10⁻⁷ m = 276.08 nm
Explanation:
The work function of a metallic surface is the minimum amount of photon energy required to release the photo-electrons from the surface of metal. The work function is given by the following formula:
Work Function = hc/λ
where,
Work Function = (4.5 eV)(1.6 x 10⁻¹⁹ J/1 eV) = 7.2 x 10⁻¹⁹ J
h = Plank's Constant = 6.626 x 10⁻³⁴ J.s
c = speed of light = 3 x 10⁸ m/s
λ = longest wavelength capable of releasing electron.
Therefore,
7.2 x 10⁻¹⁹ J = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/λ
λ = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/(7.2 x 10⁻¹⁹ J)
<u>λ = 2.7608 x 10⁻⁷ m = 276.08 nm</u>
Explanation:
It is given that,
The speed of light in vacuum is, c = 299,792,458 m/s
The permeability constant of vacuum is, 
Let 
is the permittivity of free space. The relation between 
is given by :
Hence, this is the required solution.
The force of gravity on earth is 9.807 m/s^2 (or meters per second per second).
To determine the force applied, multiply the mass of the package (5.7 kg) by the force of gravity on Earth (9.807 m/s^2).
5.7 x 9.807 = 55.86 N The answer is D.
Note: the actual force is 55.89 Newtons.
