Oraza de lumina cade sub un unghi de incidenta de 30 de grade pe o suprafata plana ce separa doua materiale transparente cu indicii de refractie 1,60 si 1,40.
calculati unghiul de refractie (din mediul cu indicele de refractie mai mic)

Explanation:

The question in english is:

A ray of light falls under an angle of incidence of 30 degrees on a flat surface that separates two transparent materials with index of refractions 1.60 and 1.40, respectively.

Calculate the angle of refraction (from the environment with the lower index of refraction)

According to Snell’s Law:  

(1)  

Where:  

is the first medium index  of refraction

is the second medium index  of refraction

is the angle of the incident ray  

is the angle of the refracted ray

We need to find from (1):

(2)  

(3)

Finally:

i would think form in reponse to tensional forces

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.