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QJEEM24Phf3bf: JEE Main 2024 Physics - Class 12 JEEM24Phf3bf Solution: In hydrogen like system the ratio of coulombian force and…

In hydrogen like system the ratio of coulombian force and gravitational force between an electron and a proton is in the order of :

Multiple Choice Options

  • A 1019
  • B 1039
  • C 1029
  • D 1036

Step-by-Step Verified Solution

To find the ratio of the Coulombic force to the gravitational force between an electron and a proton in a hydrogen-like system, we use the formulae for both forces and then divide them.

The Coulombic (electrostatic) force, FCF_C , between two charges is given by Coulomb's law:

FC=k∣q1q2∣r2F_C = k \frac{|q_1 q_2|}{r^2}

where kk is Coulomb's constant ( 8.987×109 Nm2C−28.987 \times 10^9 \, \text{Nm}^2\text{C}^{-2} ), q1q_1 and q2q_2 are the magnitudes of the charges, and rr is the distance between the charges. For a proton and an electron, q1=q2=eq_1 = q_2 = e , where ee is the elementary charge ( 1.602×10−19 C1.602 \times 10^{-19} \, \text{C} ).

The gravitational force, FGF_G , between two masses is given by Newton's law of universal gravitation:

FG=Gm1m2r2F_G = G \frac{m_1 m_2}{r^2}

where GG is the gravitational constant ( 6.674×10−11 Nm2kg−26.674 \times 10^{-11} \, \text{Nm}^2\text{kg}^{-2} ), and m1m_1 and m2m_2 are the masses of the two objects. For a proton and an electron, mp≈1.673×10−27 kgm_p \approx 1.673 \times 10^{-27} \, \text{kg} and me≈9.109×10−31 kgm_e \approx 9.109 \times 10^{-31} \, \text{kg} , respectively.

The ratio of the Coulombic to the gravitational force is therefore:

FCFG=k∣e2∣r2Gmpmer2=ke2Gmpme\frac{F_C}{F_G} = \frac{k \frac{|e^2|}{r^2}}{G \frac{m_p m_e}{r^2}} = \frac{k e^2}{G m_p m_e}

Plugging in the values:

FCFG=(8.987×109)(1.602×10−19)2(6.674×10−11)(1.673×10−27)(9.109×10−31)\frac{F_C}{F_G} = \frac{(8.987 \times 10^9) (1.602 \times 10^{-19})^2}{(6.674 \times 10^{-11}) (1.673 \times 10^{-27}) (9.109 \times 10^{-31})}

FCFG=(8.987×109)×(2.568×10−38)(6.674×10−11)×(1.523×10−57)\frac{F_C}{F_G} = \frac{(8.987 \times 10^9) \times (2.568 \times 10^{-38})}{(6.674 \times 10^{-11}) \times (1.523 \times 10^{-57})}

FCFG≈2.3×1039\frac{F_C}{F_G} \approx 2.3 \times 10^{39}

Therefore, the ratio of the Coulombic force to the gravitational force between an electron and a proton in a hydrogen-like system is on the order of 103910^{39} , making Option B the correct answer.

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