Assertion `(A) : beta-` particles are deflected more than `alpha-` particles in a given electric field.
Reason `(R) : `Charge on `alpha-` particles is larger than on `beta-`particles.

Options

A. If both `(A)` and `(R)` are correct , and `(R)` is the correct explanation of `(A)`
B. If both `(A)` and `(R)` are correct, but (R) is not the correct explanation of `(A)`
C. If `(A)` is correct, but `(R)` is incorrect.
D. If `(A)` is incorrect, but `(R)` is correct.

Explanation

To solve the question, we will analyze the assertion and reason provided step by step.

### Step 1: Understanding the Assertion
The assertion states that "beta- particles are deflected more than alpha- particles in a given electric field."

**Explanation**:
- Beta particles (β-) are electrons, which are negatively charged and much lighter than alpha particles.
- Alpha particles (α) are composed of 2 protons and 2 neutrons (essentially a helium nucleus) and are positively charged.

### Step 2: Understanding the Reason
The reason states that "the charge on alpha particles is larger than on beta particles."

**Explanation**:
- Alpha particles have a charge of +2 (due to the two protons).
- Beta particles have a charge of -1 (one electron).
- Therefore, the reason is correct; the charge on alpha particles is indeed larger than that on beta particles.

### Step 3: Analyzing the Deflection in an Electric Field
To understand why beta particles are deflected more than alpha particles, we need to consider the charge-to-mass ratio.

**Explanation**:
- The charge-to-mass ratio (q/m) is crucial for determining how much a particle will be deflected in an electric field.
- Beta particles have a much higher charge-to-mass ratio compared to alpha particles because they are much lighter (mass of an electron is significantly less than that of an alpha particle).
- This higher charge-to-mass ratio means that for the same electric field, beta particles will experience a greater acceleration and thus will be deflected more than alpha particles.

### Step 4: Conclusion
- The assertion is correct: beta particles are deflected more than alpha particles in an electric field.
- The reason is also correct: the charge on alpha particles is larger than that on beta particles.
- However, the reason does not correctly explain the assertion because the deflection is primarily due to the charge-to-mass ratio, not just the charge itself.

### Final Answer
Thus, the correct conclusion is that:
- Assertion (A) is correct.
- Reason (R) is correct, but it does not explain the assertion.
- Therefore, the answer is option B.

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