Question

Which of the following is a vector quantity?
(A) Distance
(B) Current density
(C) Power
(D) All

Answer 1

Hint: In Physics, Vector is defined as a quantity that has both magnitude and direction. It is generally represented by an arrow whose direction is the same as that of the magnitude and whose length is proportional to the magnitude of the quantity. A vector consists of both magnitude and direction but it doesn't consist of position. Keeping this in mind we can easily solve the given question.

Complete step-by step answer:
We know that a vector is a quantity with both magnitude as well as direction.
Distance is a scalar quantity as it consists of magnitude but no direction.
Power is also a scalar quantity as it consists of a magnitude but no direction.
Current density on the other hand is a vector quantity because it consists of both magnitude and direction $\overset{\to }{\mathop{J}}\,=\dfrac{I}{A}\hat{n}$.
The last option given in the question is also incorrect as Option A and Option C are incorrect.

Hence, the correct answer is Option B.

Note: Vector quantities are denoted by an arrow on the top of a variable. Current is an exception because it is considered to be a vector quantity due to its direction of flow of the electrons.