Dua buah cermin datar X dan Y saling berhadapan dan membentuk sudut 60 derajat. Seberkas cahaya menuju X dengan sudut datang 60 derajat sehingga dipantulkan ke Y. Hitunglah sudut pantul dari cahaya yang meninggalkan Y

Explanation:

The text reads;

"The two flat mirrors X and Y face each other and form a 60-degree angle. One light goes to X with the angle coming 60 degrees until it is reflected Y. Calculate the angle of reflection of the light leaving Y".

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation:

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge