Physics Basics — Set 1
Physics · भौतिकी की मूल बातें · Questions 1–10 of 50
Which of the following physical quantities is a scalar quantity?
Correct Answer: A. Mass
Mass is a scalar quantity because it only has magnitude and no direction. It remains constant regardless of the object's position in the universe. In contrast, quantities like velocity and acceleration are vectors because they require direction.
What is the SI unit of luminous intensity?
Correct Answer: A. Candela
The candela is the SI unit used to measure luminous intensity in a given direction. It is one of the seven fundamental base units in the International System of Units. This unit helps in quantifying the brightness of light sources as perceived by the human eye.
Who is credited with the discovery of the Law of Universal Gravitation?
Correct Answer: D. Isaac Newton
Isaac Newton formulated the Law of Universal Gravitation in 1687. This law states that every mass exerts an attractive force on every other mass. He published these findings in his famous work titled Philosophiæ Naturalis Principia Mathematica.
Which instrument is used to measure atmospheric pressure?
Correct Answer: D. Barometer
A barometer is a scientific instrument used specifically to measure atmospheric pressure. It was invented by Evangelista Torricelli in the 17th century. Changes in atmospheric pressure measured by this tool are often used to forecast weather changes.
The fundamental physical quantity 'Time' is measured in which SI unit?
Correct Answer: C. Second
The second is the base unit of time in the International System of Units (SI). It is defined based on the fixed numerical value of the cesium frequency. All other time units like minutes or hours are derived from the second.
Which branch of physics deals with the study of light and its properties?
Correct Answer: B. Optics
Optics is the branch of physics that studies the behavior and properties of light. It includes the study of reflection, refraction, and the interaction of light with matter. Modern optics also encompasses the study of lasers and fiber optic communication.
Who discovered X-rays in the year 1895?
Correct Answer: C. Wilhelm Röntgen
Wilhelm Röntgen discovered X-rays while experimenting with vacuum tubes. He received the first-ever Nobel Prize in Physics for this monumental discovery in 1901. X-rays are electromagnetic waves with high energy and very short wavelengths.
What is the primary unit of electric current in the SI system?
Correct Answer: C. Ampere
The ampere is the standard unit of electric current, named after Andre-Marie Ampere. It measures the flow of electric charge through a conductor over time. One ampere is equivalent to the flow of one coulomb of charge per second.
Which of these is a derived physical quantity?
Correct Answer: B. Volume
Volume is a derived quantity because it is calculated by multiplying three lengths together. Fundamental quantities like length and temperature are measured directly and do not depend on others. The SI unit for volume is the cubic meter.
The 'Parsec' is a unit of measurement for which of the following?
Correct Answer: D. Astronomical distance
A parsec is a unit of length used to measure large distances to objects outside the Solar System. One parsec is approximately equal to 3.26 light-years. It is defined using trigonometry based on the Earth's orbit around the Sun.