When a calcium atom forms an ion, it loses two electrons. What is the electrical charge of the calcium ion? a) −2 b) −1 c)+ 1 d)
1 answer:
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Answer:
Light of a shorter wavelength should be used.
Explanation:
This is studied in the phenomenon called photoelectric effect, in which light is able to release electrons from a metal, said electrons are called photoelectrons .
The experiments that have been carried out show that <u>increasing or decreasing the intensity of the light will not cause the photoelectrons to be emitted</u>, what will cause the photoelectrons to be emitted is to increase the frequency of the incident light.
And a higher frequency corresponds to a shorter wavelength according to the equation:
(where is frequency,
the speed of light, and
the wavelength)
So the answer is that the wavelength of the light must be shortened to cause the emission of electrones.
Answer:
41.667 per cent of the total kinetic energy is translational kinetic energy.
Explanation:
As the spherical shell is rolling without slipping at constant speed, the system can be considered as conservative due to the absence of non-conservative forces (i.e. drag, friction) and energy equation can be expressed only by the Principle of Energy Conservation, whose total energy is equal to the sum of rotational and translational kinetic energies. That is to say:
Where:
- Total energy, measured in joules.
- Rotational kinetic energy, measured in joules.
- Translational kinetic energy, measured in joules.
The spherical shell can be considered as a rigid body, since there is no information of any deformation due to the motion. Then, rotational and translational components of kinetic energy are described by the following equations:
Rotational kinetic energy
Translational kinetic energy
Where:
- Moment of inertia of the spherical shell with respect to its center of mass, measured in
.
- Angular speed of the spherical shell, measured in radians per second.
- Radius of the spherical shell, measured in meters.
After replacing each component and simplifying algebraically, the total energy of the spherical shell is equal to:
In addition, the moment of inertia of a spherical shell is equal to:
Then, total energy is reduced to this expression:
The fraction of the total kinetic energy that is translational in percentage is given by the following expression:
41.667 per cent of the total kinetic energy is translational kinetic energy.