Answer:
b
Explanation:
light does not need a medium
it is refracted
Light is made up of little packets of energy called photons.
electromagnetic waves
The mass of an air can be derived from the equation from density, where D=m/v. Multiply each sides by v making the equation m= Dv. Substituting the values for density and volume. m = (1.225 kg/m3)(10x20x4)m3 gives a result of 980 kg.
A fish pushes water backwards in order to move forward is a good example of Newton's 3rd Law.
Potential difference required in an electron microscope to give an electron wavelength of 4. 5 nm will be 0.063 V.
The difference in potential between two points that represents the work involved or the energy released in the transfer of a unit quantity of electricity from one point to the other is called potential difference.
The wavelength of an electron is calculated for a given energy (accelerating voltage) by using the de Broglie relation between the momentum p and the wavelength λ of an electron
lambda = 4.5 nm = 4.5 *
m
h =
J s
e = 1.6 *
C
m = 9.1 *
kg
Energy = eV
lambda = h /
= h /
=
/ (2m (eV))
V =
/ (2 m e
)
V =
/ 2 * 9.1 *
* 1.6 *
* 
V = 0.063 V
To learn more about wavelength of an electron here
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