Physics

A nuclear reactor controls nuclear reactions to produce energy, while a Geiger-Müller (GM) counter is specifically designed to detect nuclear radiation such as alpha, beta, and gamma rays.

The magnifying power of a simple microscope is inversely proportional to the focal length of its lens. Decreasing the focal length increases the angular magnification, thus increasing the magnifying power.

Cusec stands for cubic feet per second, which is a unit of flow rate or discharge. It measures the volume of water flowing past a point per second. This is widely used in hydrology and water resource management. One cusec equals one cubic foot of water flowing per second, approximately 28.3 liters per second.

A moderator in a nuclear reactor slows down fast neutrons to thermal energies, increasing the likelihood of fission reactions with the fuel nuclei. This is essential for sustaining a controlled chain reaction.

TV transmission coverage is limited primarily because the Earth is spherical, causing radio waves to travel mostly in straight lines and thus limiting the range due to the horizon. This curvature prevents signals from reaching very far distances without relay stations or satellites.

A lead ball falls more slowly through water than air primarily due to the viscous force (drag) exerted by the water, which is much higher than that in air. This viscous resistance slows down the ball's motion through the denser fluid.

A rectifier is an electrical device that converts alternating current (AC) to direct current (DC). The other options do not perform this function: an anemometer measures wind speed, a battery stores electrical energy, and a galvanometer measures electric current.

According to the theory of relativity, clocks moving at velocities close to the speed of light run slower compared to stationary clocks, a phenomenon known as time dilation.

Wind energy is primarily a form of kinetic energy because it is energy possessed by moving air (wind). This kinetic energy can be converted into mechanical energy when it turns the blades of a wind turbine. Therefore, the most precise classification of wind energy is kinetic energy.

Uranium-235 (92 U 235) is the fissile isotope of uranium used in nuclear bombs due to its ability to sustain a rapid chain reaction. Other isotopes like Uranium-238 and Uranium-234 are not suitable for this purpose.