Correct Answer - Option 1 : Planck's constant
CONCEPT:
Photon:
- According to Einstein's theory, the light propagates in the bundles of energy, each bundle is being called a photon.
- The energy of a photon is given as,
⇒ E = hν
Where E = energy of a photon, h = Planck's constant, and ν = frequency of a photon
Power
- It is defined as the rate of doing work.
- The SI unit of power is J/sec or Watt.
\(⇒ P=\frac{W}{t}=Fv\)
Where W = work, t = time, F = force and v = average velocity
Linear Momentum:
-
The linear momentum of a body is the quantity of motion contained in the body.
- It is measured in terms of the force required to stop the body in unit time.
- The SI unit of momentum is kg-m/sec.
- It is also measured as the product of the mass of the body and its velocity i.e.,
⇒ Momentum (p) = mass (m) × velocity (v)
EXPLANATION:
We know that the energy of a photon is given as,
⇒ E = hν
Where E = energy of a photon, h = Planck's constant, and ν = frequency of a photon
As we know, the SI unit energy is Joule, and the SI unit of frequency is sec-1.
Therefore,
\(\Rightarrow h=\frac{E}{\nu}=\frac{E}{\frac{1}{sec}}=\,J-sec\) -----(1)
- By equation 1 it is clear that the SI unit of Planck's constant is J-sec.
- The SI unit of power is J/sec or Watt.
- The SI unit of momentum is kg-m/sec.
- Hence, option 1 is correct.
