Explanation: At Infinity, highly enlarged, real and inverted. We know that, focus of a mirror, f = R/2, where R is the radius of curvature of the mirror. Here in this case, f = – 30/2 = -15 cm. Also, distance of the object from the mirror, u = -15 cm. It means that the object is placed at the focus of the mirror. Now it is clear that when the object is placed at focus of the mirror, the respective image will be formed at infinity. The size of the image would be highly enlarged. The nature of the image would be real and inverted.

Explanation: Aperture. Collimator – A device which narrows a beam of particles or waves. Apostilb – An obsolete unit of luminance. Meniscus – A C-shaped piece of tough, rubbery cartilage that acts as a shock absorber between the shinbone and the thigh bone.

Explanation: Polychromatic light – The light consists of a broad range of wavelengths. Examples – Mercury Light, Sunlight, laser-pumped plasma light. Monochromatic light – The light consists of only one specific wavelength. Examples – laser beam, Sodium lamps, Spark lamps. Plane polarized light – It consists of waves in which the direction of vibration is the same for all waves. Examples – laser lights and devices. Laser light – Laser (Light Amplification by Stimulated Emission of Radiation) is an artificial source of light radiation that emits a coherent beam of photons, as the source is stable in frequency, wavelength, and power.

Explanation: Reflecting telescope – Uses mirrors which cause light to reflect at different angles within the optical tube and extends the overall light path. Two major types of telescopes : Reflecting Telescopes and Refracting Telescopes (used lenses to magnify objects). Infrared telescope : Uses infrared light to detect celestial bodies.

Explanation: 25 cm. For a normal eye, the far point is at infinity and the near point of distinct vision is about 25 cm in front of the eye. Hypermetropia (far-sightedness) : When the point goes farther from 25 cm. Lens used : Convex. Myopia (Nearsightedness): Near objects appear clear, but objects farther away look blurry. Lens used: Concave.

Explanation: Red. It has the longest wavelength and least energy of the visible colors of light. Wavelength – The distance between two successive crests or troughs. Violet has the shortest wavelength. Frequency – It refers to the number of waves passing through a point per second. Violet has the highest frequency. The white light consists of 7 colors VIBGYOR (Violet – Indigo – Blue – Green – Yellow – Orange – Red).

Explanation: Iris – It gives a distinct color to the eyes. The eyeball is spherical in shape having a diameter of 23 mm. Vitreous humor present in between lens and retina. Retina contains three layers of neural cells (ganglion cells, bipolar cells, photoreceptor cells). Cornea – The front most and transparent covering of the eye. Light enters the human eye through the cornea.

Explanation: 40 cm. Using the formula: focal length (f) of convex Lens = 1/Power (P) Given, the power (P) = +2.5 diopters then focal length: f = 1 / 2.5 = 0.4 meters = 40 centimeters. Focal length of convex lens is always positive and concave lens is always negative.

Explanation: Convex Mirrors. This is because they give an erect, virtual, full size diminished image of distant objects with a wider field of view. Uses – Sunglasses, street lights.

Explanation: Virtual and erect. Convex mirror (Diverging Mirror) – It has a reflecting surface that bulges outwards, and away from the centre of curvature. Uses – Rear view mirrors, Street light reflector, etc.

Explanation: Both I and II. The focal length of the convex lens is always positive. The power of the lens = . If the focal length 1 𝑓𝑜𝑐𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ(𝑖𝑛 𝑚𝑒𝑡𝑟𝑒) is positive, then power is always positive. Uses of convex lens – Magnifying glasses, Eyeglasses, Cameras, Microscopes etc. A concave lens (diverging lens) diverges the rays incident on it. Its power is negative. Uses of concave lenses – telescopes, lasers etc.

Explanation: At infinity – At C – Highly diminished. Spherical mirrors are of two types, concave and convex. Image formation by Concave Mirror (Object Position – Image Position – Image Nature and Size) : (At Infinity – At F – Real, point size); (Beyond Center C – Between C and F (Focus) – Diminished, Real and Inverted); (On Centre – Real, inverted, and same size); (Between Centre (C) and Focus (F) – Beyond Centre – Real, inverted, and larger); (on Focus – Infinity – Real, inverted, and enlarged); (On Focal length (Between Pole and Focus) – Behind Mirror – Virtual, straight and enlarged).

Explanation: 1/v + 1/u = 1/f. There are two types of spherical mirrors : concave mirrors (If the reflective surface is on the side curved inwards) and convex mirrors (if the reflective surface is curved outwards). The lens formula is 1/v-1/u = 1/f.

Explanation: Dispersion. Refraction – Redirection of a wave as it passes from one medium to another. Reflection – When a ray of light approaches a smooth polished surface, it bounces back.

Explanation: Specular reflection is defined as light reflected from a smooth surface at a definite angle like a reflection on a bathroom mirror. Diffuse reflection is produced by rough surfaces that tend to reflect light in all directions like reading a newspaper. Multiple reflections, when we take two mirrors, a single source of light can be reflected multiple times like in a barber’s shop, we see the back of the head using multiple reflections of two mirrors.

Explanation: Germanium (Group 14, Atomic number 32) – It is a semiconductor (properties between the metals and the non-metals). Uses – as a transistor, used in wide-angle camera lenses and objective lenses for microscopes.

Explanation: Blue. So gold and copper are yellowish in color. Gold (Au, Group 11, Atomic number 79). Silver (Ag, Group 11, Atomic number 47).

Explanation: Diamond. Refractive index measures the bending of a ray of light when passing from one medium into another. The refractive index of a substance is described by the formula, n = c/v, where c is the speed of light in vacuum (3 × 108 m/s) and v is the phase velocity of light. Refractive Index – Air – 1.0003, Water – 1.333, Diamond – 2.417, Ice- 1.31, Ethyl Alcohol – 1.36, Vacuum- 1.

Explanation: Yellow. When sunlight hits the ocean, some of the light is reflected back directly but most of it penetrates the ocean surface and interacts with the water molecules.

Explanation: Plane mirror. Lateral inversion is the reversal of a mirror image where the right side of the object appears on the left side behind the mirror. Characteristics of a plane mirror – Image are Virtual and Erect. Image is formed behind the mirror. Size of the image is equal. Distance of image and mirror is equal to the distance of object and mirror.

Explanation: Scattering of light. CV Raman was awarded the Nobel prize in Physics in 1930 for his discovery of Raman effect (Scattering of light). The Tyndall effect is the phenomenon of the scattering of light by colloidal particles.

Explanation: Light-emitting Diode (LED) – A semiconductor device, which can emit light when an electric current passes through it. Working principle – Electroluminescence.

Explanation: Raman Effect. Huygens’ principle states that every point on a wavefront may be considered as a source of secondary waves. Maxwell Effect is a phenomenon of electromagnetic induction in which an electric charge, near a solenoid in which current changes slowly, feels an electromotive force (e.m.f.) even if the magnetic field is practically static inside and null outside. Rayleigh Effect is a phenomenon of scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.

Explanation: Refraction. When light moves from rarer (air) to a denser medium (water), it bends towards the normal and if it moves from a denser to a rarer medium, it bends away from the normal.

Explanation: Alpenglow. It is either the indirect sunlight reflection off of clouds after sunset or before sunrise, or to direct sunlight that occurs near sunset or sunrise.

Explanation: The number of images formed when two mirrors are placed at an angle theta (θ) to each other is given by : n = (360° / θ ) – 1 So, here, we have the mirrors placed at an angle θ = 120° ⇒ n = no. of images formed ⇒ n = ( 360° /120° ) – 1 ⇒ n = 3 – 1 ⇒ n = 2 So, a total of two images will be formed.

Explanation: Calorimetry is the process of measuring the amount of heat released or absorbed during a chemical reaction. By knowing the change in heat, it can be determined whether or not a reaction is exothermic (releases heat) or endothermic (absorbs heat). Calorimetry also plays a large part of everyday life, controlling the metabolic rates in humans and consequently maintaining such functions like body temperature.

Explanation: Spit-roasting. Braising – The cooking of meat or vegetables by heating them slowly with oil and moisture in a tightly sealed vessel. Poaching – A moist heat method of cooking by submerging food in some kind of liquid and heating at a low temperature. Stewing – A combination cooking method that uses small, uniform pieces of meat that are totally immersed in liquid and slowly simmered.

Explanation: Thermodynamics deals with the relations between heat and other forms of energy. James Clerk Maxwell – Theory of electromagnetism. Max Planck – The quantum of action (Planck’s constant). Josiah Willard Gibbs – Gibbs energy (Available energy in a system).

Explanation: The triple point of water is at 273.16 kelvin (0.01 °C or 32.02 °F) and a pressure of 611.7 Pascals.

Explanation: Joule’s. Joule’s law of heating, H = I 2RT, where, H – Heat, I – Current, R – Resistance, T – time. Hooke’s law (law of elasticity) – Discovered by the English scientist Robert Hooke in 1660, which states that, for relatively small deformations of an object, the displacement or size of the deformation is directly proportional to the deforming force or load. Faraday’s law – The magnitude of induced emf is equal to the rate of change of flux linkages with the coil.

Explanation: Longitudinal stress (axial stress). Other types of stress : Tangential stress is a type of stress that acts perpendicular to the surface of an object. Hydraulic stress is a type of stress that is caused by the pressure of a fluid. Shearing stress is a type of stress that acts parallel to the surface of an object.

Explanation: Radiation : Energy that comes from a source and travels through space at the speed of light. It has wave-like properties and can be called “electromagnetic waves”. Convection : Process of heat transfer by the movement of molecules within fluids such as gasses and liquids. Conduction : Process by which heat energy is transmitted through collisions between neighbouring atoms or molecules.

Explanation: Dew point temperature. It is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity of 100%.

Explanation: 212°F. Steam point is the temperature at which the maximum vapour pressure of water is equal to one atmosphere. It has a value of 100°C on the Celsius scale.

Explanation: Thermodynamics. During energy transfer, the energy moves from the hotter object to the colder object. This means that the hotter object will cool down and the colder object will warm up. The energy transfer will continue until both objects are at the same temperature. Heat is measured in joules (J).

Explanation: Thermal expansion is a phenomenon due to which the metal expands when heated and contracts when cooled. The Eiffel Tower gets taller by up to 6 inches during the summer.

Explanation: George Gabriel Stokes. Daniel Bernoulli – Known for Bernoulli’s principle. According to this principle, an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid’s potential energy. Evangelista Torricelli – Known for his invention of the barometer, a device used to measure atmospheric pressure. Heinrich Gustav Magnus – Known for Magnus effect, an observable phenomenon that is commonly associated with a spinning object moving through the air or a fluid.

Explanation: Daniel Bernoulli. Torricelli’s law – The parting speed of a jet of water, based on the distance below the surface at which the jet starts, assuming no air resistance, viscosity, or other hindrance to the fluid flow. Pascal’s law – The pressure applied to an enclosed fluid will be transmitted without a change in magnitude to every point of the fluid and the walls of the container. Poiseuille’s law – It gives the pressure drop in an incompressible and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of a constant cross-section.

Explanation: Reverse Osmosis. Filtration is the process in which solid particles in a liquid or gaseous fluid are removed. Boiling is the process by which a liquid turns into a vapor when it is heated to its boiling point. Distillation is a process involving the conversion of a liquid into vapor that is subsequently condensed back to liquid form.

Explanation: 10.8. Relative density is a comparative measure of the density of a substance to the density of a reference substance (Usually Water).

Explanation: Neutral point : The point at which the resultant magnetic field is zero. It is a point where the magnetic field produced due to a bar magnet is completely balanced by the horizontal component of Earth’s magnetic field. Magnetic Field – The region around a magnetic material or a moving electric charge within which the force of magnetism acts. Types of magnets : Permanent magnet, temporary magnet and electromagnet.

Explanation: Heinrich Friedrich Lenz. Lenz’s law – An induced electric current flows in a direction such that the current opposes the change that induced it. Lenz’s law is used in electromagnetic brakes and induction cooktops. It is also applied to electric generators, AC generators. Christian Johann Doppler – Doppler’s effect refers to the change in wave frequency during the relative motion between a wave source and its observer. Sir David Brewster – Brewster law is a statement that says that when unpolarized light falls on an interface, the reflected light is completely polarized if the angle of incidence is a specific angle called the Brewster’s angle.

Explanation: Valid for only point charge. Coulomb’s Law : The electrical force between two charged objects is directly proportional to the product of the quantity of charge on the objects and inversely proportional to the square of the separation distance between the two objects. F = , where {Q1 – quantity 𝑘 𝑄1 𝑄2 𝑑 2 of charge on object 1 (in Coulombs), Q2 – quantity of charge on object 2 (in Coulombs), and d – distance of separation between the two objects (in meters). k – proportionality constant (the Coulomb’s law constant)}. Value of k – 8.988×109 Nm2/C2 .

Explanation: Faraday’s law. Coulomb’s law states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Kirchhoff’s laws – The algebraic sum of all the currents meeting at a point in a circuit is equal to zero. Laplace’s law – The tension in the walls of a hollow sphere or cylinder is dependent on the pressure of its contents and its radius.

Explanation: 6.25 × 1018 . Electric Current – The rate of flow of electrons in a conductor. SI Unit – Ampere (A). Conductors are defined as the materials or substances that allow electricity to flow through them. Examples – Human body, aqueous solutions of salts and metals like iron, silver and gold. Insulators are materials that restrict the free flow of electrons from one particle to another. Examples – Plastic, Wood, Rubber and Glass.

Explanation: Nichrome. Resistivity – It is the measure of the resistance ability of a material to oppose the flow of current. Electrical resistivity is the reciprocal of electrical conductivity. High Resistivity materials – Ebonite, Tungsten, Carbon. High conductivity materials – Copper, iron, gold, aluminium, and silver.

Explanation: Steel. Permanent magnets are made from special alloys (ferromagnetic materials) such as iron, nickel and cobalt, several alloys of rare-earth metals and minerals such as lodestone; Used in headphones, loudspeakers, MRI Scanners, hard disc drives, generators, transducers. A freely suspended magnet always rests in north-south (N-S) direction. Magnetite (Fe3O4) – An ore of iron that has magnetic properties (ferrimagnetic).

Explanation: 18Ω. In series connection of resistors (Here, 3 Ω, 4 Ω, 5 Ω, 6 Ω), Current through each resistor is same. Voltage drop across each resistor is proportional to its resistance. The total resistance is equal to the sum of the individual resistances. Equivalent resistance Rn = R1 + R2 + R3 + R4 = 3 Ω + 4 Ω + 5 Ω + 6 Ω = 18Ω.

Explanation: Magnetic fields (Symbol B or H, Unit – Tesla) : William Gilbert discovered that the Earth is a magnet. The strength of magnetic field lines depends on how close the magnetic field lines are. Some properties related to magnetic field lines are: Strongest near the poles (N or S), never crosses each other, always make closed loops.