Physics

One mega ohm (MΩ) is equal to 10^6 ohms, which means one million ohms. This is a standard unit conversion in electrical resistance. Among the options given, option A (10^6 ohm) correctly represents one mega ohm. The original correct answer was C (10^7 ohm), which is incorrect. Therefore, the correct answer is option A.

Cadmium is commonly used in control rods because it is an excellent neutron absorber, which helps regulate the rate of nuclear fission in a reactor. Graphite and heavy water act as moderators, not control rods, so they do not control the reaction by absorbing neutrons.

The Uncertainty Principle was formulated by Werner Heisenberg, which states that certain pairs of physical properties cannot both be known to arbitrary precision simultaneously.

A dyne is the unit of force in the centimeter-gram-second (CGS) system. It is defined as the force required to accelerate a mass of one gram at a rate of one centimeter per second squared.

Dr. Abdus Salam was a renowned Pakistani physicist who worked in theoretical physics and had connections with prominent scientists including Albert Einstein's circle. He is the most famous Pakistani scientist associated with Einstein's work. Riazuddin Siddiqui was also a notable Pakistani physicist but did not work directly under Einstein.

Charles Algernon Parsons invented the steam turbine in 1884, which greatly improved the efficiency of steam engines. The other options are unrelated to the invention of the steam turbine.

The escape velocity from Earth is approximately 11.2 miles per second, which is closest to option C (12 miles/second). This is the minimum speed needed for a body to overcome Earth's gravitational pull without further propulsion.

A dioptre is the unit of measurement for the optical power of a lens or curved mirror, which is the reciprocal of the focal length measured in meters. Therefore, it measures lens refractive power.

Electrons are the charge carriers in metals because they are loosely bound to atoms and can move freely, unlike protons which are tightly bound in the nucleus. Their small size and negative charge are true but not the primary reason for their mobility in metals.

The escape velocity from Earth's surface is approximately 11.2 kilometers per second, which converts to about 7 miles per second. This is the minimum speed needed for an object to escape Earth's gravitational pull without further propulsion. The other options (22, 15, and 12 miles per second) are higher than the actual escape velocity. Therefore, the correct answer is D (7 miles per second).

Raindrops fall through the air and reach a terminal velocity that depends on their size and shape, so different droplets have different ultimate velocities. This is why option A is correct.

The magnetic field inside the core of a toroid depends on both the current flowing through the coil and the number of turns per unit length. According to Ampère's law, the magnetic field at a radius r inside the toroid is given by B = (μ * N * I) / (2πr), where N is the total number of turns, I is the current, and μ is the permeability of the core material. Thus, the magnetic field depends on the current and the number of turns, not just one or the other. The field is not zero inside the toroid; it is confined within the core region and varies with radius.

Conductivity is the measure of a material's ability to conduct electric current, and its unit is the mho, which is the reciprocal of the ohm (unit of resistance).

A parsec is a unit of distance used in astronomy to measure large distances to objects outside our solar system, approximately equal to 3.26 light-years.

A Newton metre (N·m) is the SI unit of torque, which measures the rotational force applied at a distance from a pivot point. It is not used for substance, length, or work (work is measured in joules).

Gamma rays are electromagnetic radiation and have no charge, so they are not deflected by electric or magnetic fields, unlike alpha and beta rays which are charged particles and do get deflected.

The Sun's energy is produced by nuclear fusion, where hydrogen nuclei combine to form helium, releasing vast amounts of energy. This process powers the Sun and other stars.

Among the given planets, Mercury has the lowest acceleration due to gravity because it is smaller and less massive compared to Mars, Jupiter, and Neptune. Jupiter and Neptune are gas giants with very high gravity, and Mars has higher gravity than Mercury due to its larger mass.

The Curie (Ci) is a unit used to measure radioactivity, specifically the rate of radioactive decay. It is not related to heat, work, energy, or power.

Lux is the SI unit of illumination or illuminance, which measures the amount of luminous flux per unit area. It quantifies how much light is received on a surface.

The observation of merging black holes billions of light-years away led to the first direct detection of gravitational waves, confirming a major prediction of Einstein's general relativity. This discovery opened a new way to observe cosmic events.

The SI unit of dipole moment is coulomb-meter (Cm), which represents the product of charge and distance. Debye is a commonly used unit in chemistry but is not an SI unit. Weber is the SI unit of magnetic flux, and Coulomb is the unit of electric charge.

Stars appear to twinkle because their light passes through Earth's turbulent atmosphere, causing the light to refract multiple times and change direction slightly, which makes the stars seem to flicker or twinkle.

Plasma is the most abundant form of matter in the universe, making up stars and interstellar matter, far exceeding the amounts of solids, liquids, or gases.

A Tokamak is a device used in nuclear fusion research that uses magnetic fields to confine plasma in the shape of a torus, enabling the conditions necessary for fusion reactions.