Physics Basics — Set 4
Physics · भौतिकी की मूल बातें · Questions 31–40 of 50
What is the SI unit of Work and Energy?
Correct Answer: C. Joule
The Joule is the SI unit for both work and energy, named after James Prescott Joule. One Joule is defined as the work done when a force of one Newton moves an object by one meter. It is also the unit used to measure heat energy.
Who formulated the laws of planetary motion?
Correct Answer: C. Johannes Kepler
Johannes Kepler published three laws of planetary motion in the early 17th century. These laws describe how planets move in elliptical orbits around the Sun. His work was crucial for Newton's later development of the theory of gravity.
Which mirror is commonly used as a rear-view mirror in vehicles?
Correct Answer: A. Convex mirror
Convex mirrors are used in vehicles because they provide a wider field of view. They always form an erect and diminished image of the objects behind the vehicle. This helps drivers see a larger area of the road than a flat mirror would.
The SI unit of Thermodynamic Temperature is?
Correct Answer: B. Kelvin
The Kelvin is the primary unit of temperature in the International System of Units. It is an absolute scale where zero Kelvin represents the complete absence of thermal energy. It is named after the physicist William Thomson, 1st Baron Kelvin.
Which of the following is used to measure very high temperatures, like that of the Sun?
Correct Answer: C. Pyrometer
A pyrometer is a type of remote-sensing thermometer used to measure high temperatures. It determines the temperature of a surface from the spectrum of the thermal radiation it emits. It is used in industries and astronomy where direct contact is impossible.
What is the value of Acceleration due to gravity on Earth's surface?
Correct Answer: B. 9.8 m/s²
The standard acceleration due to gravity on Earth is approximately 9.8 meters per second squared. This value can vary slightly depending on the altitude and latitude of the location. It represents the rate at which an object accelerates when falling freely near the surface.
Who is the inventor of the Mercury Barometer?
Correct Answer: A. Evangelista Torricelli
Evangelista Torricelli, an Italian physicist, invented the mercury barometer in 1643. He demonstrated that the height of mercury in a tube changes with atmospheric pressure. This invention proved that air has weight and can exert pressure.
Which physical law explains the working of a hydraulic lift?
Correct Answer: D. Pascal's Law
Pascal's Law states that pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid. Hydraulic lifts use this principle to multiply force and lift heavy loads. This discovery is a fundamental concept in the field of fluid mechanics.
What is the SI unit of Power?
Correct Answer: A. Watt
The Watt is the SI unit of power, defined as one Joule of work done per second. It is named after James Watt for his contributions to the development of the steam engine. Power is a measure of the rate at which energy is transferred or converted.
Which of the following colors of light has the shortest wavelength?
Correct Answer: D. Violet
Violet light has the shortest wavelength and the highest frequency in the visible spectrum. Red light, on the other end, has the longest wavelength and the lowest frequency. The wavelengths of visible light range from about 380 to 750 nanometers.