Correct: D. Convex

A convex mirror (also known as a "fisheye" or diverging mirror) is used for side-view and rear-view mirrors in vehicles. These mirrors bulge outward, which allows them to show a wider field of view than a flat mirror, helping drivers see more of the area behind and to the side of their car.

Correct: C. Ampere

The Ampere (often shortened to "Amp" or symbol A) is the SI unit of electric current. It measures the rate of flow of electric charge through a circuit. One ampere is equal to one "Coulomb" of electrical charge passing a point in one second. It was named after Andr?-Marie Ampère, a French physicist who is considered the father of electromagnetism.

Correct: A. Action-Reaction

Newton's Third Law of Motion states that "For every action, there is an equal and opposite reaction." This means that whenever one object exerts a force on a second object, the second object exerts a force of equal magnitude and opposite direction back on the first object.

Correct: C. Einstein

Albert Einstein is the physicist who proposed the Theory of Relativity, which is composed of Special Relativity (1905) and General Relativity (1915). His work fundamentally changed our understanding of space, time, and gravity, introducing the famous equation E=mc, which shows that energy and mass are interchangeable. General relativity explains gravity not as a force, but as a curvature of space-time caused by mass.

Correct: B. 300,000 km/s

The speed of light in a vacuum is approximately 299,792,458 meters per second (often rounded to 300,000 km/s or 186,000 miles per second. According to Einstein's theory of relativity, this is the universal speed limit; nothing with mass can travel faster than light. It is a fundamental constant of physics denoted by the letter 'c'.

Correct: B. Ammeter

An Ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in Amperes (A), hence the name. For an ammeter to measure current correctly, it must be connected in "series" with the circuit so that the full current flows through it.

Correct: B. Converges them

A convex lens (also known as a converging lens) is thicker in the middle than at the edges and causes parallel light rays that pass through it to converge at a single point called the "focal point." These lenses are used to correct farsightedness and are the primary components in magnifying glasses, cameras, and telescopes.

Correct: A. Temperature

Temperature is the measure of the average kinetic energy of the particles in a substance. When you heat an object, its atoms and molecules move faster, increasing their kinetic energy and causing the temperature to rise. This is why things feel hot when their particles are vibrating rapidly and cold when they are moving slowly.

Correct: C. 373 K

The boiling point of water is 373.15 Kelvin (which is equal to 100C or 212F. The Kelvin scale is the absolute temperature scale used by scientists; it starts at absolute zero 0 K and has the same unit size as the Celsius scale. You can convert Celsius to Kelvin simply by adding 273.15.

Correct: C. Convex

A convex mirror is used as a rearview mirror in vehicles because it always forms an erect (upright) and diminished image, which provides a much wider field of view compared to a plane mirror. This allows drivers to see a larger area of the traffic behind them.

Correct: C. Transverse

A light wave is a transverse electromagnetic wave. Unlike sound waves, which are longitudinal and require a medium, light waves consist of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of travel.

Correct: B. Disperses it

A prism disperses (splits) white light into its constituent colors-red, orange, yellow, green, blue, indigo, and violet. This happens because different colors of light travel at different speeds through the glass, causing them to refract (bend) at different angles.

Correct: B. Ohm's Law

Ohm's Law relates voltage V, current I, and resistance R with the formula V = I R. It states that the current passing through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature remains constant.

Correct: D. 20Hz to 20kHz

The standard frequency range of human hearing is typically 20 Hz to 20,000 Hz 20 kHz. Sounds below 20 Hz are called infrasound, and sounds above 20,000 Hz are called ultrasound.

Correct: B. Barometer

A barometer is a scientific instrument used to measure atmospheric pressure. Changes in air pressure are often used in weather forecasting to predict storms or clear skies. Evangelista Torricelli is credited with inventing the mercury barometer in 1643.

Correct: A. Chemical

A battery stores chemical energy, which is converted into electrical energy through an electrochemical reaction when the battery is connected to a circuit. This process involves the movement of electrons from the negative terminal to the positive terminal.

Correct: C. Evaporation

Evaporation is the process of a liquid turning into a gas at temperatures below its boiling point. This occurs because some molecules at the surface of the liquid gain enough kinetic energy to escape into the air. It is a cooling process, which is why we sweat to lower our body temperature.

Correct: A. Protons + Neutrons

The mass number of an atom is the total number of protons and neutrons in its nucleus. Electrons are so light that their mass is not included in the mass number. Atoms of the same element with different mass numbers are called isotopes.

Correct: A. Geothermal

Geothermal energy is energy that comes from the heat generated deep inside the Earth. This heat can be used to produce electricity or to provide direct heating for buildings.

Correct: D. Maximum population

Carrying capacity is the maximum population size of a biological species that a specific environment can sustain indefinitely, given the food, habitat, water, and other available resources. If a population exceeds its carrying capacity, the ecosystem may become degraded.

Correct: B. Second Law

The Second Law of Thermodynamics introduces the concept of entropy as a measure of disorder or randomness within a system. It dictates the direction of spontaneous processes, implying that heat will always flow from a hotter body to a colder one unless work is performed. This law is often cited as the reason for the 'arrow of time,' as it suggests the universe is moving toward a state of maximum disorder.

Correct: B. Heisenberg Uncertainty Principle

Werner Heisenberg formulated this principle to describe the inherent limitations of measurement at the subatomic level. The more precisely we know where a particle is, the less we know about how fast it is moving, and vice versa. This is not due to a flaw in our instruments but is a fundamental property of wave-particle duality.

Correct: D. Gravity

Gravity is surprisingly the weakest force; for example, a small refrigerator magnet can overcome the entire Earth's gravitational pull to hold up a piece of paper. While it dominates at cosmic scales due to its infinite range and cumulative mass, at the atomic level, it is overshadowed by the other three forces. Physicists are still working to find a way to unify gravity with quantum mechanics in a 'Theory of Everything.'

Correct: B. Bernoulli's Principle

Bernoulli's Principle is a consequence of the law of conservation of energy in fluid dynamics. It explains how wings generate lift, as the air moving faster over the curved top of the wing creates a lower pressure area compared to the bottom. This principle is also why a shower curtain pulls toward you when the water is running fast.

Correct: C. Work Function

The work function is a specific property of each metal that determines how much energy a photon must have to trigger the photoelectric effect. If the incoming light has a frequency too low, no electrons will be ejected, regardless of how bright the light is. This concept was pivotal in establishing the particle nature of light.

Correct: C. Alpha Decay

Alpha decay occurs in heavy, unstable atoms like Uranium or Radium as they seek a more stable configuration. The emission of an alpha particle reduces the atomic number by two and the mass number by four, effectively changing the element into a different one. While alpha particles can be stopped by a single sheet of paper, they are extremely dangerous if the radioactive source is inhaled or ingested.

Correct: B. Planck Constant

The Planck constant (h) is a central value in quantum mechanics, approximately 6.626 x 10^-34 joule-seconds. It defines the 'scale' of the quantum world and is used to calculate the energy of light (E=hf). In 2019, the Planck constant replaced the physical 'Le Grand K' cylinder as the basis for defining the kilogram.

Correct: B. Time Dilation

Time dilation is a verified consequence of Einstein's theory, stating that the faster an object moves, the slower time passes for it compared to a stationary observer. This effect becomes significan't only at speeds approaching the speed of light, but it must be accounted for even in everyday technology like GPS. Without relativistic corrections, GPS coordinates would drift by several kilometers every day.

Correct: B. Graphene

Graphene is a single layer of carbon atoms arranged in a hexagonal 'honeycomb' lattice, making it the thinnest known material. Despite being only one atom thick, it is about 200 times stronger than steel and is an excellent conductor of both heat and electricity. Researchers are exploring its use in ultra-fast electronics, water filtration, and advanced batteries.

Correct: B. Meissner Effect

The Meissner Effect is a defining characteristic of superconductivity, distinct from simply having zero resistance. When a material becomes a superconductor, it creates internal currents that perfectly cancel out any external magnetic field, forcing the field lines to go around it. This is what allows for 'quantum levitation' seen in demonstrations with magnets and liquid nitrogen.

Correct: A. Resonant Frequency

Resonant frequency is a property determined by the physical characteristics of a system, such as the length of a pendulum or the tension in a guitar string. When a periodic force is applied at this specific frequency, the amplitude of the oscillations can grow dramatically, a phenomenon known as resonance. This is how a singer can break a wine glass by matching its natural pitch.

Correct: C. Entanglement

Quantum entanglement occurs when two particles are created or interact in a way that their quantum states cannot be described independently. When the property of one particle is measured, the other's property is determined immediately, even if they are separated by light-years. This phenomenon is a key resource for the development of quantum computers and secure quantum communication.

Correct: C. Boyle's Law

Boyle's Law is mathematically expressed as P1V1 = P2V2, meaning that as you compress a gas into a smaller space, its pressure increases. This principle is what allows us to breathe, as the expansion of our lungs creates a lower pressure area that draws in air. It is one of the component laws that make up the Ideal Gas Law (PV=nRT).

Correct: B. Specific Heat Capacity

Specific heat capacity varies widely between materials; for example, water has a very high specific heat, which is why it is such an effective coolant and why coastal areas have milder climates. Metals generally have low specific heats, meaning they heat up and cool down very quickly. This property is crucial for thermal management in everything from cooking pans to spacecraft.

Correct: C. Diffraction

Diffraction occurs with all types of waves, including light, sound, and water waves. It is most noticeable when the size of the obstacle or opening is similar to the wavelength of the wave; this is why you can hear someone talking around a corner but you cannot see them. In science, diffraction patterns are used to determine the structure of crystals and DNA molecules.

Correct: C. Concave Mirror

Concave mirrors (converging mirrors) are designed so that parallel light rays reflecting off their surface meet at a focal point. They are used in car headlights to create a strong beam and in makeup mirrors to provide a magnified image. In high-end astronomy, huge concave mirrors are preferred over lenses because they don't suffer from 'chromatic aberration' (color blurring).

Correct: C. Period

The period (T) is the inverse of the frequency (f), measured in seconds per cycle. For example, if a wave has a frequency of 50 Hz, its period is 0.02 seconds. Understanding the period is vital in fields ranging from music theory to the timing of electrical signals in computer processors.

Correct: C. Coulomb's Law

Coulomb's Law states that the force is proportional to the product of the charges and inversely proportional to the square of the distance between them. Similar to gravity, it follows an inverse-square law, but unlike gravity, the electrical force can be both attractive and repulsive. This law is the starting point for the study of electrostatics.

Correct: B. Concave Lens (Diverging Lens)

A concave lens diverts parallel light rays so that they appear to originate from a single focal point in front of the lens. These lenses are primarily used to correct myopia (nearsightedness) by pushing the focal point of the eye further back onto the retina. They are also used in peepholes and some types of flashlights to broaden the beam.

Correct: C. Deposition

Deposition is the thermodynamic reverse of sublimation, occurring when gas molecules lose thermal energy and bond directly into a solid structure. The most common natural example is the formation of frost on a cold window or on grass during a winter night. In high-tech manufacturing, 'chemical vapor deposition' is used to create ultra-thin layers of material for microchips.