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PhysicsClass 10CBSE

What is centripetal force?

Centripetal force acts on an object in circular motion, always directed towards the centre of the circle.Formula: F = mv²/rSituationForce acting as centripetalStone on a stringTensionEarth orbiting SunGravityCar turning a cornerFrictionElectron around nucleusElectrostatic force</tbo

PhysicsClass 10CBSE

What is gravitational force?

Gravitational force is the attractive force between any two objects with mass.Newton's Law: F = G × (m₁ × m₂) / r²G = 6.674 × 10⁻¹¹ N m²/kg²Always attractive, acts over infinite range, does not need a medium.Weakest of four fundamental forces, but dominant at astronomical scales.<

PhysicsClass 10CBSE

What is a longitudinal wave?

A longitudinal wave has particles vibrating parallel to the direction of wave propagation, creating alternating compressions and rarefactions.Requires a material medium cannot travel through vacuum.Classic example: Sound wavesFeatureLongitudinalTransverse<

PhysicsClass 10CBSE

What is the critical angle?

The critical angle is the angle of incidence in a denser medium at which the refracted ray just grazes the interface (90°), beyond which total internal reflection occurs.Formula: sin(C) = 1/nExample (Glass, n = 1.5): sin(C) = 1/1.5 → C ≈ 41.8°Applications: Optical fibres, diamond sparkle, periscopes/binoculars, mirages.The critical angle is the threshold angle of incidence beyond which light undergoes total interna

PhysicsClass 10CBSE

What is focal length?

Focal length is the distance between the optical centre of a lens/mirror and its principal focus.Symbol: f | Unit: metres (m)Convex lens/concave mirror: positive fConcave lens/convex mirror: negative fRelationship with Power: P = 1/f (in Dioptre

PhysicsClass 10CBSE

What is dispersion of light?

Dispersion is the splitting of white light into its constituent colours (VIBGYOR) when passing through a prism.Different colours have different wavelengths → different refractive indices → different bending.Violet bends most; red bends least.Examples: Rainbow, prism spectrum, diamond sparkle,

PhysicsClass 10CBSE

What is refractive index?

Refractive index measures how much light slows down when passing from vacuum into a medium.Formula: n = c / v (speed of light in vacuum / speed in medium)MediumRefractive IndexVacuum1.00Water1.33Glass~1.5Diamond2.42Diamond's high refractive index (2.42) c

PhysicsClass 10CBSE

What is a magnifying glass used for?

A magnifying glass makes small objects appear larger using a convex (converging) lens. When an object is placed within the focal length, the lens produces a virtual, erect, and magnified image.Uses: Reading fine print, examining lab specimens, jewellery inspection, philately, forensic investigation, watchmaking.A magnifying glass uses a convex lens to create a virtual, enlarged image of nearby objects, widely used in science, medicine, and everyday tasks.

PhysicsClass 10CBSE

What is the photoelectric effect?

The photoelectric effect is the ejection of electrons from a metal surface when light of sufficient frequency strikes it. Explained by Einstein using photons.Depends on frequency, not intensity higher frequency = more energetic photons = faster electrons.Increasing intensity only increases the number of ejected electrons, not their speed.<li data

PhysicsClass 10CBSE

What is a fuel cell and how does it work?

A fuel cell converts the chemical energy of hydrogen directly into electrical energy through reaction with oxygen like a battery that never runs out as long as fuel is supplied.How it works:At the anode: H₂ → H⁺ + electrons (electrons travel through external circuit = electricity)At the cathode: O₂ + H⁺ + ele

PhysicsClass 10CBSE

What is blood pressure?

Blood pressure is the force exerted by blood against the walls of arteries, measured in mmHg.Normal: 120/80 mmHg (systolic / diastolic)Systolic = force during heartbeat; Diastolic = force between beats.High blood pressure = hypertension strains arteries and heart.<

PhysicsClass 10CBSE

What is reflex action?

A reflex action is a rapid, automatic response to a stimulus controlled by the spinal cord no conscious brain processing needed.Reflex arc: Receptor → Sensory neuron → Spinal cord → Motor neuron → EffectorExample: Pulling hand from hot object before feeling pain. Brain receives information after the reflex occurs.A reflex action is an involuntary, instant response controlled by the spinal cord through a reflex arc, bypassing consci

PhysicsClass 10CBSE

What is the difference between reflex action and walking?

FeatureReflex ActionWalkingControlSpinal cordBrain (cerebellum + cerebrum)Conscious thoughtNot requiredRequired initiallySpeedExtremely fastModeratePurposeProtection from sudden harmPurposeful movementReflex actions are involuntary and immed

PhysicsClass 10CBSE

What is light? What are sources of light?

Light is a form of electromagnetic radiation visible to the human eye. It travels in waves and also behaves as particles called photons (wave-particle duality).Properties:Speed: 299,792,458 m/s (≈3 × 10⁸ m/s) in vacuum — the fastest speed in the universeVisible wavelength range: 380 nm (violet) to 700 nm (red)<li data-list-item-id="edbe8

PhysicsClass 10CBSE

What is friction?

Friction is the force that resists relative motion between two surfaces in contact. It always acts in the direction opposite to motion or intended motion.Types of friction:TypeDescriptionExampleStatic frictionOpposes motion before an object starts movingPushing a heavy box that does not yet moveKinetic (sliding) frictionActs wh

PhysicsClass 10CBSE

Causes of friction

Interlocking of microscopic surface irregularities (asperities) — primary causeMolecular adhesive forces (van der Waals forces between contact surfaces)Normal force — greater pressing force = greater interlocking = more friction (f = μN)<li

PhysicsClass 10CBSE

What is are force?

Force is any push or pull that changes or tends to change the state of rest or uniform motion of a body.F = ma (Newton's Second Law) | SI unit: Newton (N) = 1 kg·m/s²Four fundamental forces of nature:GravitationalElectromagneticStrong Nuclear<li data-list-item-id="e9d9

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