Explanation :
When an electron jumps from one energy level to another, the energy of atom gets changed.
If a photon gets absorbed, the electron will move to higher energy levels and then fall back to the lower energy levels. Then each time a photon will be absorbed whose energy is given by difference between the initial and final energy levels i.e
In Balmer series, the transition is from higher energy levels to n = 2.
So, the necessary condition for Balmer series is that the electron should be at first excited state or n = 2 level as shown in figure.
Answer:
ФE = 9.403W
Explanation:
In order to calculate the magnitude of the electric flux trough the sheet, you use the following formula:
(1)
A: area of the rectangular sheet = (0.400m)(0.600m) = 0.24m^2
E: magnitude of the electric field = 95.0N/C
θ: angle between the direction of the electric field and the normal to the surface of the sheet
You replace the values of the parameters in the equation (1):

The magnitude of the electric flux is trough the sheet is 9.403W
Answer: 
Explanation:
Given
Mass 
Spring constant 
Compression in the spring 
When the mass leaves the spring, the elastic potential energy of spring is being converted into kinetic energy of mass i.e.

The kinetic energy of the mass is 1.102 J.
Answer:
The distance between the two slits is 1.2mm.
Explanation:
The physicist Thomas Young establishes, through its double slit experiment, a relationship between the interference (constructive or destructive) of a wave, the separation between the slits, the distance between the two slits to the screen and the wavelength.
(1)
Where
is the distance between two adjacent maxima, L is the distance of the screen from the slits,
is the wavelength and d is the separation between the slits.
If light pass through two slits a diffraction pattern in a screen will be gotten, at which each bright region corresponds to a crest, a dark region to a trough, as consequence of constructive interference and destructive interference in different points of its propagation to the screen.
Therefore, d can be isolated from equation 1.
(2)
Notice that it is necessary to express L and
in units of millimeters.
⇒ 
⇒ 
Hence, the distance between the two slits is 1.2mm.