Answer: a) 274.34 nm; b) 1.74 eV c) 1.74 V
Explanation: In order to solve this problem we have to consider the energy balance for the photoelectric effect on tungsten:
h*ν = Ek+W ; where h is the Planck constant, ek the kinetic energy of electrons and W the work funcion of the metal catode.
In order to calculate the cutoff wavelength we have to consider that Ek=0
in this case h*ν=W
(h*c)/λ=4.52 eV
λ= (h*c)/4.52 eV
λ= (1240 eV*nm)/(4.52 eV)=274.34 nm
From this h*ν = Ek+W; we can calculate the kinetic energy for a radiation wavelength of 198 nm
then we have
(h*c)/(λ)-W= Ek
Ek=(1240 eV*nm)/(198 nm)-4.52 eV=1.74 eV
Finally, if we want to stop these electrons we have to applied a stop potental equal to 1.74 V . At this potential the photo-current drop to zero. This potential is lower to the catode, so this acts to slow down the ejected electrons from the catode.
Answer:
259.62521 seconds
Explanation:
= Mass of astronaut = 87 kg
= Mass of wrench = 0.57 kg
= Velocity of astronaut
= Velocity of wrench = 22.4 m/s
Here, the linear momentum is conserved
Time = Distance / Speed
The time taken to reach the ship is 259.62521 seconds
The work done by the gravitational force = 0
Given the mass of the box = 40 kg
The box is initially at rest.
Distance moved by the applied force = 5m
Force applied = 130 N
Co-efficient of friction between the box and floor = 0.3
The box is moved only in the horizontal direction by the applied force.
Gravitational force is applied in a direction perpendicular to the applied force. hence it doesn't do any work on the box.
Therefore, the work done by the gravitational force is zero.
Learn more about the gravitational force at brainly.com/question/862529
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Answer:
Emissions from power plants that burn fossil fuels increase atmospheric carbon dioxide, which is absorbed by the ocean.
Explanation:
Fossil fuels are burnt in power plants in order to produce energy. These fossil fuels contain carbon. Combustion of these fossil fuels emits oxides of carbon into the atmosphere. The oxides of carbon are carbon II oxide and carbon dioxide.
Carbon dioxide can be absorbed by the ocean to form carbonic acid according to the reaction equation;
CO2(aq) + H2O(l) ------> H2CO3(aq)
This is an anthropogenic activity which increases ocean acidification.
