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.

When a train passes at high speed, the air pressure near the train decreases rapidly, creating a suction effect that tends to pull nearby objects, like the boy, towards the train, but the dominant effect is the air pushed forward causing the boy to be pushed away from the train. Hence, the boy is more likely to fall away from the train due to the air displacement.

Weightlessness inside a spacecraft occurs because both the astronaut and the spacecraft are in free fall, effectively falling around the Earth together, which creates the sensation of zero weight. Gravity still acts on them, but there is no normal force acting on the astronaut.

To see her full image in a plane mirror, the minimum length of the mirror must be half her height, which is 3 feet for a 6 feet tall lady. This is because the angles of incidence and reflection allow the full image to be seen in a mirror half the person's height.

Myopia, or nearsightedness, occurs when the eye focuses images in front of the retina. It is corrected using a concave lens, which diverges light rays so they focus correctly on the retina.

Approximately one third of an iceberg's volume remains above the water surface because ice is less dense than seawater. This means about two thirds of its mass is submerged, leaving roughly one third visible above water.

Stealth technology primarily involves methods such as special coatings and design features that reduce an aircraft's radar cross-section, making it less visible to radar detection. Option B correctly identifies this as a coating that reduces radar visibility.

In nuclear reactions, fission is the process where a heavy nucleus splits into smaller nuclei, while fusion is the process where two or more light nuclei combine to form a heavier nucleus. Therefore, the reaction described where nuclei fuse to form a heavy nucleus is called fusion nuclear reaction.

At ordinary temperatures, sound travels approximately 1120 feet per second. For an echo to be distinctly heard, the reflected sound must return after at least 0.1 seconds, meaning the reflecting surface must be at least 56 feet away (since sound travels to the surface and back, the total distance is 112 feet, so one way is 56 feet).

The Aurora Borealis occurs when charged particles from the sun collide with gases in the Earth's ionosphere, causing the characteristic red and green lights. The ionosphere is the layer where these interactions primarily happen, not the troposphere, mesosphere, or stratosphere.

Fast Breeder Reactors typically use mixed carbide fuels such as Uranium-Plutonium carbide because of their high breeding ratio and better thermal conductivity compared to oxides. While Uranium-Plutonium oxide is also used in some reactors, carbide fuel is more characteristic of fast breeder reactors.

Blue shift refers to the Doppler effect where the wavelength of light from an object decreases, making it appear bluer when the object moves towards the observer or vice versa. This is a well-established concept in physics and astronomy.

A parsec is a unit of distance used in astronomy, equal to about 3.26 light-years. It measures the distance at which one astronomical unit subtends an angle of one arcsecond.

The escape velocity from Earth at the surface is approximately 11.2 kilometers per second, which converts to about 7 miles per second. This is the minimum velocity needed for a body to escape Earth's gravitational pull without further propulsion. Among the given options, 7 miles per second (option C) is the closest and correct value for Earth's escape velocity.

Twinkling of stars occurs due to the refraction of starlight as it passes through the Earth's turbulent atmosphere, causing the light to bend and vary in intensity and position.

Ultraviolet (UV) light has enough energy to ionize atoms and molecules, placing it in the category of ionizing radiation rather than non-ionizing. Visible light does not have sufficient energy to ionize, and 'None' is incorrect.

Alpha particles consist of two protons and two neutrons tightly bound together, which makes them compact clusters of these nucleons. This is a well-established fact in nuclear physics.

The coulomb (C) is the SI unit of electric charge, not velocity, temperature, or mass. Therefore, none of the given options A, B, or C are correct, making option D the correct choice.

A neutron is a neutral particle because it has no electric charge, unlike alpha particles, electrons, and protons which are charged particles.

Although the satellite moves at a uniform speed, its direction is continuously changing as it orbits the Earth, which means it is undergoing centripetal acceleration. Therefore, the motion is accelerated, not without acceleration.

Beta particles are high-speed electrons emitted during radioactive decay, which is why option B (Electrons) is correct.

A generator is a device that converts mechanical energy into electrical energy by electromagnetic induction, making option D correct. Motors convert electrical energy into mechanical energy, transformers change voltage levels of electrical energy, and coils are components, not devices that convert energy forms.

Vacuum tubes were widely used in early electronics for amplification and switching but have been replaced by transistors, which are smaller, more reliable, and energy-efficient semiconductor devices.

The SI unit of electric charge is the Coulomb, which quantifies the amount of electric charge transported by a current of one ampere in one second.

France produces the highest percentage of its electricity from nuclear power plants, generating a significant portion of its energy from atomic reactors, more than any other country. While the USA has more reactors and total nuclear energy production, France relies more heavily on nuclear energy as a share of its total electricity.