Physics - Study Mode
[#1031] Hydroscope is an instrument that shows changes in:
Correct Answer
(D) None of these
Explanation
Solution: 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.
[#1032] Unit of impedance is ________
Correct Answer
(A) Ohm
Explanation
Solution: The unit of impedance, like that of resistance, is the ohm.
[#1033] Stress can be defined as ________ quantity.
Correct Answer
(D) Tensor
Explanation
Solution: 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.
[#1034] In spherical polar coordinates (l, q, a), q denotes the polar angle around z-axis and a denotes the azimuthal angle raised from x-axis . Then the y-component of P is given by
Correct Answer
(A) Psinq sina
Explanation
Solution: 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
[#1035] Two vectors are said to be equal if
Correct Answer
(C) Both magnitude and direction are same
Explanation
Solution: Two vectors and are said to be equal, if they have the same magnitude and direction, Also same positions of their initial points.