1. Assertion: A scalar has magnitude only.
Reason: A scalar quantity is one that must be dimensionless.
(1) Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
(2) Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
(3) Assertion is correct but Reason is incorrect.
(4) Assertion is incorrect but Reason is correct.
2. Assertion: If a physical quantity is a vector, it must have direction.
Reason: Current has a direction therefore it is a vector quantity.
(1) Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
(2) Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
(3) Assertion is correct but Reason is incorrect.
Answer (2)
To analyze the assertions and reasons given in the question, we need to review the definitions and properties of scalar and vector quantities in physics.
1. Assertion: A scalar has magnitude only.
Reason: A scalar quantity is one that must be dimensionless.
A scalar is defined as a quantity that has only magnitude and no direction. Examples of scalars include mass, temperature, and energy. These quantities have magnitude but no particular direction in space, which differentiates them from vector quantities. However, a scalar is not necessarily dimensionless. For example, mass is a scalar and has the unit of kilograms, which is a dimension. Therefore, the reason given is incorrect.
Consequently, the chosen option for this is: (3) Assertion is correct but Reason is incorrect.
2. Assertion: If a physical quantity is a vector, it must have direction.
Reason: Current has a direction therefore it is a vector quantity.
A vector is a quantity that has both magnitude and direction. Common examples include velocity, force, and displacement. The assertion that a vector must have a direction is indeed true. However, the reason provided is incorrect. Although electric current does flow in a specific direction, it is considered a scalar quantity, not a vector. This is because it does not obey the vector addition rules (like the parallelogram law of vector addition).
Therefore, the chosen option for this is: (3) Assertion is correct but Reason is incorrect.
For the first question, the correct option is (3) because the assertion is true while the reason is false. For the second question, the correct option is again (3) given that the assertion is true but the reason is incorrect. Both assertions correctly identify properties of scalar and vector quantities in physics.
;
