Add then divide the hint clearly backs it up two so yeahh
Answer:
The SI unit of force is Newton.
Explanation:
Newton is denoted by N.
Force can be defined as the pull or push which change or try to change the state of a body from motion to rest or rest to motion in a straight line.
Solution:
The relation between the potential difference and the electric field between the plates of the parallel plate capacitor is given by :

Differentiating on both the sides with respect to time, we get

Therefore, the rate of the electric field changes between the plates of the parallel plate capacitor is given by :


V/m-s
As per the question the wavelength of spectral line of the neutral hydrogen atom is 21 cm.
Spectral line of hydrogen atom will be observed when an electron will jump from higher excited to the ground state. If E is the energy of the ground state and E' is the energy of the higher excited state,the energy emitted when electron will jump from higher excited to ground state is E'-E.
As per Planck's quantum theory -

Where f is the frequency of emitted radiation and h is the Planck's constant.Actually this energy emitted is also electromagnetic in nature. We know that all the electromagnetic radiation will move with the same velocity which is equal to the velocity of light.
The velocity of light c= 3×10^8 m/s.Hence the velocity of wave corresponding to this spectral line is 3×10^8 m/s.
We know that velocity of a wave is the product of frequency and wavelength of that corresponding wave. Mathematically we can write it as-

[
is the wavelength of the wave ]
It is given that wavelength =21 cm=0.21 m
The frequency is calculated as -




Hence the antenna will be tuned to a frequency of 14.2857×10^8 Hz
Here Hertz[ Hz] is the unit of frequency.