In the photoelectric effect, the energy of the incoming photon (E=hf) is used in part to extract the photoelectron from the metal (work function) and the rest is converted into kinetic energy of the photoelectron:
![hf = \phi + K](https://tex.z-dn.net/?f=hf%20%3D%20%5Cphi%20%2B%20K)
where
h is the Planck constant
f is the frequency of the incident light
![\phi](https://tex.z-dn.net/?f=%5Cphi)
is the work function of the material
K is the kinetic energy of the photoelectron.
The photoelectron generally loses part of its kinetic energy inside the material; however, we are interested in its maximum kinetic energy, that is the one the electron has when it doesn't lose energy, so we can rewrite the previous equation as
![K_{max} = hf - \phi](https://tex.z-dn.net/?f=K_%7Bmax%7D%20%3D%20hf%20-%20%5Cphi)
The work function is (in Joule)
![\phi = (4.97 eV)(1.6 \cdot 10^{-19} J/eV)=7.95 \cdot 10^{-19} J](https://tex.z-dn.net/?f=%5Cphi%20%3D%20%284.97%20eV%29%281.6%20%5Ccdot%2010%5E%7B-19%7D%20J%2FeV%29%3D7.95%20%5Ccdot%2010%5E%7B-19%7D%20J)
and using the data of the problem, we find the maximum kinetic energy of the photoelectrons
Answer:
0.3 N
Explanation:
i = 400 A
B = 30 x 10^-6 T
L = 25 m
Force due the current carrying conductor placed in a magnetic field
F = B i L SinФ
where, Ф be the angle between length vector and magnetic field vector
F = 30 x 10^-6 x 400 x 25 = 0.3 N
Answer:
Isothermal process = Temperature is constant
Explanation:
- As the name implies, iso means same and thermal is related to temperature.
- In isothermal process, the temperature of the system remains constant throughout.
- The exchange of heat takes place such that the thermal equilibrium is maintained.
- Hence, the correct option is (c) " temperature is constant".
An observer stands at the tip of the dark blue arrow in the diagram the view of the sun from the observer’s point of you is the following
Explanation:
1.The region of complete shadow is called the umbra and the region of diffuse shadow is called the penumbra. These shadows are formed on the Earth during a solar eclipse and From the umbra we see a total eclipse while from the penumbra only a partial eclipse is visible.
2.There are four different types of solar eclipse, namely Partial eclipse, Annular eclipse, Total Eclipse and Hybrid Eclipse. A partial solar eclipse occurs when only part of the Sun is covered by the Moon which appears to take a “bite” out of the Sun.
3.Solar eclipses can only occur during a New Moon when the Moon moves between Earth and the Sun and the 3 celestial bodies form a straight line: Earth–Moon–Sun. There are between 2 and 5 solar eclipses every year. There are 3 kinds of solar eclipses: total, partial, and annular.
4.You can see from the two diagrams that there are two types of shadow; a crisp edged one formed by a point source of light and a rather more fuzzy one that is formed by a larger source. The region of deep, total shadow is called the UMBRA and the region of partial shadow is called the PENUMBRA.
5.umbra. The very darkest part of a shadow is the umbra. It's where the light source is completely blocked by the object in front of it.
6.The Moon's shadow actually has two parts:
Penumbra. The Moon's faint outer shadow. Partial solar eclipses are visible from within the penumbral shadow.
Umbra. The Moon's dark inner shadow. Total solar eclipses are visible from within the umbral shadow.
Answer;
B. Increased levels of carbon dioxide, a greenhouse gas, leads to increased phytoplankton growth.
Explanation;
-A combination of warm water, high nutrient levels, and adequate sunlight may cause a harmful algae bloom. These blooms may damage aquatic ecosystems by blocking sunlight and depleting oxygen that other organisms need to survive.
-Algae blooms have been increasing globally, and climate change may be playing a role in the increment. For instance, during the warm summer season or when water is warmer, some harmful types of algae to grow faster than other, more benign varieties.
-Additionally, the warmer surface water also prevents water from mixing vertically, allowing algae to grow thicker and faster.