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 laws of vector addition.

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Answer 1

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Electric current though has direction as well as magnitude does not follow laws of vector addition so it is not a vector.

However, velocity is a vector quantity. But, velocity of light is not a vector quantity as it does not follow laws of vector addition. 

The ratio of the inertial mass to gravitational mass is equal to

1) Inertial mass. This is mainly defined by Newton's law, the all-too-famous F = ma, which states that when a force F is applied to an object, it will accelerate proportionally, and that constant of proportion is the mass of that object. In very concrete terms, to determine the inertial mass, you apply a force of F Newtons to an object, measure the acceleration in m/s^2, and F/a will give you the inertial mass m in kilograms. 

2) Gravitational mass. This is defined by the force of gravitation, which states that there is a gravitational force between any pair of objects, which is given by Gm1m2/r^2

where G is the universal gravitational constant,

 m1 & m2 are the masses of the two objects, and r is the distance between them. This, in effect defines the gravitational mass of an object. 

The inertial mass & gravitational mass is equivalent & ratios of inertial mass to gravitational mass = 1 to a high degree of accuracy (experimental finding).

Answer 2

Answer:

There are two quantities that we often loosely refer to as current. The first is the current density J, which is the sum over all charge carriers of the product of the charge and velocity divided by the volume.

J = n<qv>

I’m using Bold type to indicate vectors, and <> to denote an average. n is the number of charge carriers per volume, q is the charge per charge carrier, and v is the velocity of the charge carrier. Since the velocity is a vector quantity, J is definitely a vector.

The second quantity is the current I, which is the flux of charge per time through a surface. (flux = flow through) To fully define the flux I have to specify the direction normal to the surface,as for any surface there are two directions that are perpendicular(i.e.normal) to the surface. Formally, the current is then

I = |J| A cos (theta)

where theta is the angle between J and the direction normal to the surface and A is the area of the surface. The | | here indicate the magnitude of the vector inside.(I’ve assumed the current is uniform across the surface here to keep things simple.)

Since I only depends on scalar quantities, current is a scalar , and technically it has no direction. Informally, though, we often refer to the “direction of the current” when we really mean the direction of the current density.