Question

Assertion (A): Electric current and velocity of light both have direction as well as the magnitude but still they are not considered as vectors.
Reason (R): Electric current and velocity of light do not follow the laws of vector addition.
A) Both A and R are correct and R is the correct explanation of A
B) Both 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

Answer 1

Hint : Electric current though has direction as well as the magnitude does not follow laws of vector addition so it is not a vector. However, velocity is a vector quantity. But, the velocity of light is not a vector quantity as it does not follow the laws of vector addition.

Complete step by step answer:
Electric current and velocity of light are both scalar quantities.
Any quantity that is termed as a vector quantity should have both magnitude and direction. But this is not the only condition that has to be satisfied. The quantity should satisfy the law of vectors such as the parallelogram law of vector addition, triangle law of vector addition, etc to be a vector quantity.
In the case of electric current, when two different electric currents meet at a junction, the net sum of the two currents will not be due to vector addition but will be rather due to the algebraic sum of the two currents. Hence electric current is not a vector quantity.
Similarly, when two light rays combine, they also do not follow the laws of vector addition so it is also not a vector quantity.
Hence option (A) is correct since the assertion is correct and the reason statement provides the correct reason for it.

Note:
Defining the direction of electric current and velocity of light is very helpful to us in physical situations which is why they have directions. However, since the quantities don’t behave as other vector quantities mainly they don’t follow the law of vector addition, they can’t be called vector quantities.