Some Basic Questions Of Science And Engineering

Explanation
A step-up motor increases voltage because it is designed to convert a lower voltage input into a higher voltage output. This is achieved through the use of a transformer or other voltage boosting mechanism within the motor. By increasing the voltage, the motor is able to generate a higher level of power and drive larger loads. Increasing the current or power is not the primary function of a step-up motor.

Explanation
The unit of inductance is Henry. Inductance is a property of an electrical circuit that opposes changes in current flow. It is measured in Henry (H), named after the American scientist Joseph Henry. Inductance is used to store energy in magnetic fields and is commonly found in devices such as inductors and transformers. Farad is the unit of capacitance, Ohm is the unit of resistance, and Mho (reciprocal of Ohm) is the unit of conductance.

Explanation
The frequency of a DC signal is zero because DC stands for direct current, which means that the current flows in only one direction with a constant magnitude. Unlike AC (alternating current), which changes direction periodically, DC does not have any oscillation or frequency. Therefore, the correct answer is zero.

Explanation
C programming was invented in 1977.

Explanation
The keyword "Return" is used to transfer the control from a subroutine to the main function. When a subroutine is called within a program, it performs its tasks and then returns the control back to the point where it was called. This allows the main function to continue executing the remaining code after the subroutine call.

Explanation
Engineer's Day is celebrated in India in honor of Sir Mokshagundam Visvesvaraya. He was a renowned engineer, statesman, and the Diwan of Mysore. Visvesvaraya made significant contributions to the field of engineering and played a crucial role in the development of India's infrastructure. He was instrumental in the construction of several dams, bridges, and irrigation systems. His expertise and dedication to engineering have made him a symbol of inspiration for aspiring engineers in India. Therefore, Engineer's Day is celebrated to commemorate his achievements and to acknowledge the importance of engineering in society.

Explanation
Hydrogen is not a greenhouse gas because it does not trap heat in the Earth's atmosphere. Greenhouse gases, such as carbon dioxide, nitrous oxide, and methane, are responsible for the greenhouse effect, which causes the Earth's temperature to rise. Hydrogen, on the other hand, is a highly flammable gas and does not contribute to the greenhouse effect.

Explanation
Marie Curie is the correct answer because she is widely recognized as the discoverer of the radioactive element radium. Curie, along with her husband Pierre Curie, conducted extensive research on radioactivity and made significant contributions to the field. In 1898, they successfully isolated radium from a uranium ore sample, marking a major breakthrough in the understanding of radioactive elements. Marie Curie's pioneering work in this area earned her numerous accolades, including becoming the first woman to win a Nobel Prize and the only person to win Nobel Prizes in two different scientific fields.

Explanation
Alfred Nobel is the correct answer because he invented and patented dynamite. Alfred Nobel, a Swedish chemist and engineer, developed dynamite in the late 19th century. His invention revolutionized the construction and mining industries, as it provided a safer and more efficient way to handle explosives. Nobel's invention of dynamite had a significant impact on various fields, earning him a place in history as one of the most influential inventors.