Practice MCQ Questions and answers on Physics-GK

The siemens (symbol: S) is the derived unit of electric conductance, electric susceptance, and electric admittance in the International System of Units (SI).

Hydroscope is an optical device for enabling a person to see an object at a considerable distance below the surface of water by means of a series of mirrors enclosed in a steel tube. Hydrophone is an instrument used for recording sound under water. It is the underwater equivalent of a microphone that measures pressure fluctuations, and these are usually converted to sound pressure level (SPL), a logarithmic measure of the mean square acoustic pressure.

The unit of impedance, like that of resistance, is the ohm.

Stress is defined as resisting force per unit area of an element, on which load is applied. Stress is always perpendicular to a cross-section in the element. It is neither scalar (it cannot be numerically added), nor is it a vector (it does not follow the triangle rule of vector addition). It is a tensor quantity because it describes things happening in two directions simultaneously.

The Cartesian Coordinates can be retrieved from spherical coordinates (l,q,a) by:
X = r.sinq.cosa
Y = r.sinq.sina
Z = r.sinq
Using the same we get for P,
Y = P.sinq.sina

Two vectors and are said to be equal, if they have the same magnitude and direction, Also same positions of their initial points.

In physics, a vector quantity is a physical quantity that has both magnitude and direction. Area is an example of a vector quantity because it has both magnitude (e.g., square meters) and direction (e.g., the orientation of the area in three-dimensional space).

The other options are not vector quantities:
Option B: Power is a scalar quantity because it has magnitude but no direction.
Option C: Electric Current is a scalar quantity. While it involves the motion of charged particles, it is described by magnitude only.
Option D: Energy is a scalar quantity. While energy can be associated with physical processes, it is also described by magnitude only.
Option E: None of these is not the correct answer because, as explained, Option A (Area) is indeed a vector quantity.

So, the correct answer is Option A: Area, as it is a physical quantity that possesses both magnitude and direction, which are characteristics of vector quantities.

Density is not a vector quantity.

Speed is not a vector quantity. It has only magnitude and no direction and hence it is a scalar quantity.

Sound waves cannot travel in the vacuum of space because there is no medium to transmit these mechanical waves.