Assertion : If dot product and cross product of P and Q are zero, it implies that one of the vector P and Q must be null vector. Reason : A null vector is a vector of zero magnitude.

Correct answer: (B) If both assertion and reason are true but reason is not the correct explanation of assertion.. As per question, |A · B|=|A × B|=0 This is possible if either A=0 or B=0 . Magnitude of a null vector is zero.

Q120 / 180 · AIIMS 2018 (27 May) · Physics

Assertion : If dot product and cross product of $\vec{P}$ and $\vec{Q}$ are zero, it implies that one of the vector $\vec{P}$ and $\vec{Q}$ must be null vector. Reason : A null vector is a vector of zero magnitude.

A
If both assertion and reason are true and reason is the correct explanation of assertion.
Correct answer
B
If both assertion and reason are true but reason is not the correct explanation of assertion.
C
If assertion is true but reason is false.
D
If both assertion and reason are false.

Solution

As per question, $|\vec{A} \cdot \vec{B}|=|\vec{A} \times \vec{B}|=0$ This is possible if either $A=0$ or $B=0$. Magnitude of a null vector is zero.

Hence, the correct answer is option: 'B'.

Assertion : If dot product and cross product of $\vec{P}$ and $\vec{Q}$ are zero, it implies that one of the vector $\vec{P}$ and $\vec{Q}$ must be null vector. Reason : A null vector is a vector of zero magnitude.

Solution

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