Answer and Explanation:
Data provided in the question
Force = 50N
Length = 5mm
diameter = 2.0m = 
Extended by = 0.25mm = 
Based on the above information, the calculation is as follows
a. The Stress of the wire is

here area of circle = perpendicular to the are i.e cross-sectional i.e
= 
= 
Now place these above values to the above formula

= 15.92 MPa
As 1Pa = 1 by N m^2
So,
MPa = 10^6 N m^2
b. Now the strain of the wire is

= 
Air and water ima air bender
It's the only star in the sky (visible from the northern hemisphere) that never seems to move. It stays at almost exactly the same point in the sky, while the other stars all circle around it once a day.
Answer:
LAW 1 : For a given metal and frequency, the number of photoelectrons emitted is directly proportional to the intensity of the incident radiation.
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LAW 2: For a given metal, there exists a certain frequency below which the photoelectric emission does not take place. This frequency is called threshold frequency.
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LAW 3: For a frequency greater than the threshold frequency, the kinetic energy of photoelectrons is dependent upon frequency or wavelength but not on the intensity of light.
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LAW 4: Photoelectric emission is an instantaneous process. The time lag between incidence of radiations and emission of electron is 10^-9 seconds.
Explanation: