NEET
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- NEET
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- Atomic Physics
NEET · Physics · Atomic Physics
Given below are two statements: one is labelled as Assertion (A)...
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): In the Geiger-Marsden experiment, for a given impact parameter and incident kinetic energy, a target nucleus with a larger atomic number () will scatter an -particle by a larger angle.
Reason (R): The Coulomb repulsive force between the -particle and the target nucleus is inversely proportional to the atomic number of the target nucleus.
In the light of the above statements, choose the most appropriate answer from the options given below.
Assertion (A): In the Geiger-Marsden experiment, for a given impact parameter and incident kinetic energy, a target nucleus with a larger atomic number () will scatter an -particle by a larger angle.
Reason (R): The Coulomb repulsive force between the -particle and the target nucleus is inversely proportional to the atomic number of the target nucleus.
In the light of the above statements, choose the most appropriate answer from the options given below.
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
C. (A) is true but (R) is false
Step-by-step solution
The impact parameter is given by the relation .
For a fixed impact parameter and incident kinetic energy , the product is constant. If the atomic number increases, must decrease. Since is a decreasing function for angles between and , the scattering angle must increase. Thus, the Assertion (A) is true.
The Coulomb repulsive force between an -particle (charge ) and a nucleus (charge ) is . This force is directly proportional to the atomic number , not inversely proportional. Thus, the Reason (R) is false.
Therefore, (A) is true but (R) is false.
Answer: (A) is true but (R) is false
For a fixed impact parameter and incident kinetic energy , the product is constant. If the atomic number increases, must decrease. Since is a decreasing function for angles between and , the scattering angle must increase. Thus, the Assertion (A) is true.
The Coulomb repulsive force between an -particle (charge ) and a nucleus (charge ) is . This force is directly proportional to the atomic number , not inversely proportional. Thus, the Reason (R) is false.
Therefore, (A) is true but (R) is false.
Answer: (A) is true but (R) is false