Question

The scalar quantity among the follows is:
A) Weight of body
B) Temperature gradient
C) Elementary area
D) Magnetic field strength

Answer 1

Hint: Scalar quantities are those quantities that only have a magnitude and no direction associated with them. In contrast, vector quantities have both magnitude and direction associated with them. The product of a scalar and a vector quantity is a vector quantity.

Complete step by step answer
In option (A), the weight of a body is a vector quantity. The weight of a body is the product of the mass of the body and the gravitational acceleration experienced by the object. Since the gravitational acceleration is a vector quantity, the product of mass which is a scalar quantity and gravitational acceleration is also a vector quantity.
In option (B), the temperature gradient is the difference in temperature of a system in a given particular direction per unit length. Since there is again a direction associated with it, the temperature gradient is a vector quantity.
In option (C), the elementary area of an object is simply its area and it has no direction associated with it. So, the elementary area is a scalar quantity.

Hence option (C) is the correct choice.

Note
Magnetic field strength also has a direction associated with it so it is also not a scalar quantity. In option (A), while mass is a scalar quantity, weight is not. So we must be careful in not selecting option (A) as the correct choice. The elementary area is simply the area of an object or the surface area of a 3D object which has no direction associated with it and so we must not be confused by the word ‘elementary’ in the option.