Answer:
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Explanation:
The gravitational force of the earth keeps us bound to the earth. Gravitational force between earth and sun makes the earth move around the sun. Gravitational force between moon and earth makes the moon go around the earth.
<span>This is because Helium
has two valence electrons compared to Hydrogen which has only one. Helium has
more energy levels for an electron to jump thus more spectral lines to occur.
The spectral lines relating to each change of energy level would be more
grouped together and hence the greater chance of them falling in the visible
range.</span>
<span>The answer is: ultraviolet
The energy (E) of a photon is directly proportional to its frequency f, by Planck's
formula: E = hf, where h is Planck's constant (6.625 * 10**-34 joule-second).
The frequency is inversely proportional to the wavelength w by: f = c/w, where
c is the speed of light, 3.0 * 10**8 meters per second.
Combine these formulas and we see that the energy is inversely proportional to
the wavelength by: E = hc/w
If the energy is inversely proportional to the wavelength, a photon with twice the
energy has half the wavelength of our 442-nm. photon in this example.
So its wavelength is 221 nm. which is in the ultraviolet range.</span>
lf a heavy point mass is suspended by a weightless, inextensible and perfectly flexible string from a rigid support, then this arrangement is called simple pendulum.
In practice, however, these requirements cannot be fulfilled. So we use a practical pendulum.
A practical pendulum consists of a small metallic solid sphere suspended by a fine silk thread from a rigid support. This is the practical simple pendulum which is nearest to the ideal simple pendulum.
Note :
The metallic sphere is called the bob.
When the bob is displaced slightly to one side from its mean position and released, it oscillates about its mean position in a vertical plane.
