Answer:
As you may know, each element has a "fixed" number of protons and electrons.
These electrons live in elliptical orbits around the nucleus, called valence levels or energy levels.
We know that as further away are the orbits from the nucleus, the more energy has the electrons in it. (And those energies are fixed)
Now, when an electron jumps from a level to another, there is also a jump in energy, and that jump depends only on the levels, then the jump in energy is fixed.
Particularly, when an electron jumps from a more energetic level to a less energetic one, that change in energy must be compensated in some way, and that way is by radiating a photon whose energy is exactly the same as the energy of the jump.
And the energy of a photon is related to the wavelength of the photon, then we can conclude that for a given element, the possible jumps of energy levels are known, meaning that the possible "jumps in energy" are known, which means that the wavelengths of the radiated photons also are known. Then by looking at the colors of the bands (whose depend on the wavelength of the radiated photons) we can know almost exactly what elements are radiating them.
Answer:
Waves can be measured using wavelength and frequency. ... The distance from one crest to the next is called a wavelength (λ). The number of complete wavelengths in a given unit of time is called frequency (f). As a wavelength increases in size, its frequency and energy (E) decrease.
Answer:
Explanation:
Energy of electron in n = 4 state
= - 13.6/4² =- 0.85 eV
So energy needed to extract it from atom = .85 eV.
The Voyager and Pioneer flybys of the 1970s and 1980s provided rough sketches of Saturn’s moons. But during its many years in Saturn orbit, Cassini discovered previously unknown moons, solved mysteries about known ones, studied their interactions with the rings and revealed how sharply different the moons are from one another.
To solve the problem it is necessary to take into account the concepts related to simple pendulum, i.e., a point mass that is suspended from a weightless string. Such a pendulum moves in a harmonic motion -the oscillations repeat regularly, and kineticenergy is transformed into potntial energy and vice versa.
In the given problem half of the period is equivalent to 1 second so the pendulum period is,

From the equations describing the period of a simple pendulum you have to

Where
g= gravity
L = Length
T = Period
Re-arrange to find L we have

Replacing the values,


In the case of the reduction of gravity because the pendulum is in another celestial body, as the moon for example would happen that,




In this way preserving the same length of the rope but decreasing the gravity the Period would increase considerably.