Physical Geography — Earth Features & Climate

Why This Chapter Matters

Physics shows up in IBPS Clerk, IBPS PO, and SBI Clerk General Awareness papers in a thin, predictable slice, usually 1 to 3 marks, tucked inside a "Science and Technology" or "Static GK" mix rather than as a dedicated section. That sounds small until you notice something: almost every aspirant preparing for banking exams skips physics entirely, assuming it belongs to SSC and Railways papers alone. This creates a strange opportunity. The questions that do appear are rarely calculation-heavy; they test whether you know that sound needs a medium to travel, or that a fuse wire protects a circuit, or what unit measures electric current. Spend two focused hours here and you can convert nearly every physics question you meet into a guaranteed mark, while most of the room around you guesses.

The single biggest mistake aspirants make with this topic is treating it like the SSC CGL physics syllabus, memorizing formulas, numerical problems, and derivations that banking exams never ask for. Banking GA tests recognition and everyday application, not computation. You are far more likely to see "which instrument measures atmospheric pressure" than "calculate the force given mass and acceleration." This chapter is built for that exact target: no equations to solve, just the conceptual and factual core that banking papers actually draw from, explained in a way that sticks.

Units and Measurements: The Language Science Speaks

Every measurable quantity in physics needs a unit, a fixed reference that everyone agrees on, the way a rupee has a fixed value regardless of who is spending it. Without standard units, a "long" distance in one country could mean something entirely different in another, and trade, engineering, and science would collapse into confusion.

The world's scientific community settled on the SI system (Système International d'Unités, French for International System of Units) as the common language for measurement. SI has seven base units, each measuring one fundamental physical quantity that cannot be broken down further into other units.

Quantity	SI Unit	Symbol
Length	metre	m
Mass	kilogram	kg
Time	second	s
Electric current	ampere	A
Temperature	kelvin	K
Amount of substance	mole	mol
Luminous intensity	candela	cd

Exam trap: Students often answer "gram" for the SI unit of mass out of habit, since grams appear on every kitchen scale and grocery packet. The correct SI base unit is the kilogram, not the gram. This single confusion costs more marks than any other unit-related question in banking GA papers.

Memory hook: "Meri Kaki Sadaa Ache Kapde Maange." Read the first letter of each word: M (metre-length), K (kilogram-mass), S (second-time), A (ampere-current), A (again, for kelvin, remember it as the "aunty's" second A for temperature), K (kelvin can also be tagged here), M (mole). A simpler personal version works too: just remember the acronym "M-K-S-A-K-M-C" stands for metre, kilogram, second, ampere, kelvin, mole, candela, and build your own sentence around those seven letters in that exact order. The point of any such hook is not the phrase itself but forcing your brain to hold all seven in one fixed sequence, so that under exam pressure you can count them off on your fingers instead of guessing.

Beyond the seven base units, physics also uses derived units, built by combining base units. Speed is distance divided by time, so its unit is metre per second (m/s). Force is measured in newton (N), energy and work in joule (J), pressure in pascal (Pa), power in watt (W), and frequency in hertz (Hz). These derived units appear constantly in daily life without most people noticing: your electricity bill is calculated in units of energy (kilowatt-hour), your weather report gives pressure in millibars (related to pascal), and your phone charger's rating is printed in watts.

A quantity described only by a number, like 5 kilograms or 10 seconds, is called a scalar quantity. A quantity that needs both a number and a direction to make sense, like "10 newtons pushing east," is called a vector quantity. Distance, speed, mass, energy, and time are scalars. Displacement, velocity, acceleration, and force are vectors. Think of a scalar as answering "how much," while a vector answers "how much, and which way."

Basic Mechanics: How Things Move and Why

Mechanics is the branch of physics that studies motion and the forces causing it. Banking exams touch this area lightly but consistently, usually through Newton's laws and simple everyday concepts rather than problem-solving.

Sir Isaac Newton formulated three laws of motion in the 17th century that still describe how ordinary objects behave today.

The first law, often called the law of inertia, states that an object at rest stays at rest, and an object in motion continues moving at constant velocity, unless an external force acts on it. This is why passengers standing in a bus lurch forward when the driver brakes suddenly: your body was moving with the bus, and it resists the sudden change in motion even as the bus itself slows down. That resistance to a change in motion is inertia, and it scales with mass, which is why a fully loaded truck is far harder to stop than an empty scooter.

The second law connects force, mass, and acceleration: force equals mass multiplied by acceleration (F = ma). A heavier object needs more force to achieve the same acceleration as a lighter one. This is intuitive to anyone who has pushed a loaded shopping cart versus an empty one at a supermarket; the loaded cart resists your push far more, even though your effort feels the same.

The third law states that for every action, there is an equal and opposite reaction. When you jump off a small boat onto a riverbank, the boat pushes back and drifts away from the bank, sometimes dramatically. Your foot pushed the boat backward with the same force the boat pushed you forward. Rockets use this exact principle: burning fuel is expelled downward at high speed, and the rocket is pushed upward with equal force.

Exam trap: Aspirants frequently mix up the first and second laws when asked "which law explains why a seatbelt is necessary." The correct answer is the first law (inertia), since your body wants to keep moving forward even after the car stops suddenly in a collision, and the seatbelt is the external force that halts you safely. The second law explains force and acceleration relationships, not this scenario.

Gravity is the force of attraction between any two masses, and on Earth it gives every object a downward acceleration of approximately 9.8 metres per second squared, often rounded to 9.8 m/s² or approximated as 10 m/s² in quick GK contexts. This is why a dropped coin and a dropped stone, ignoring air resistance, hit the ground at the same time despite their different weights, a fact famously demonstrated by Galileo (legend places it at the Leaning Tower of Pisa, though historians debate whether this specific demonstration actually happened).

Friction is the force that opposes relative motion between two surfaces in contact. Without friction, you could not walk (your foot would simply slide backward with no grip), a car could not brake, and a pencil could not write on paper. Friction is why ball bearings and lubricating oil are used in machines: they reduce friction between moving metal parts, cutting down wasted energy and wear. Yet friction is also why machines need oiling and why shoes wear out, converting useful motion into heat that dissipates uselessly.

Pressure is force applied per unit area. A sharp knife cuts more easily than a blunt one not because it applies more force, but because that force is concentrated onto a much smaller area, producing far higher pressure. This is the same reason a nail has a sharp point (to concentrate force and pierce material) while a wide, flat foundation is used under heavy buildings (to spread weight over a large area and reduce pressure on the soil below).

Work in physics has a specific meaning distinct from its everyday sense. Work is done only when a force causes displacement in the direction of that force. If you push against a wall for an hour and it does not move, you may feel exhausted, but in the physics sense, you have done zero work, because there was no displacement. This distinction between physical effort and physics-defined work trips up many aspirants who assume "trying hard" always counts as work.

Electricity: Currents, Circuits, and Everyday Devices

Electricity questions are among the most frequently repeated in banking GA physics, largely because they connect directly to devices readers use daily.

Electric current is the flow of electric charge, measured in amperes (A). Voltage (or potential difference) is the "push" that drives current through a circuit, measured in volts (V). Resistance opposes the flow of current, measured in ohms (Ω). These three quantities are linked by Ohm's Law, formulated by Georg Simon Ohm: voltage equals current multiplied by resistance (V = IR).

Think of an electric circuit like a water pipe system. Voltage is like the water pressure pushing water through the pipe. Current is like the actual flow rate of water, how much passes a point per second. Resistance is like a narrowing or obstruction in the pipe that restricts flow. A higher pressure (voltage) pushes more water (current) through the same pipe, while a narrower pipe (higher resistance) reduces flow for the same pressure. This water analogy, though imperfect at a deep physical level, makes Ohm's Law intuitive to recall under exam stress.

A circuit needs to be a closed loop for current to flow. If any point in the loop is broken, called an open circuit, current stops completely, which is exactly how a switch works: flipping it off physically breaks the loop.

Series and parallel circuits are a recurring exam theme. In a series circuit, components are connected one after another in a single loop, so the same current flows through every component, and if one component fails (like a single blown bulb in an old-style series fairy light string), the entire circuit breaks and everything stops working. In a parallel circuit, components are connected across separate branches, so each component gets its own path, and if one fails, the others keep working independently. This is exactly why modern household wiring uses parallel circuits: if one bulb blows, the rest of the house does not go dark.

Exam trap: A frequently asked question is "why does a single failed bulb in old serial decorative lights turn off the whole string, but a failed bulb at home does not affect other rooms." The answer hinges entirely on series versus parallel wiring, and confusing these two circuit types is the single most common mistake in this topic.

A fuse is a safety device containing a thin wire that melts and breaks the circuit when current exceeds a safe limit, protecting household wiring and appliances from overheating and fire during a short circuit or overload. A short circuit happens when current finds an unintended low-resistance path, often because of damaged insulation letting live and neutral wires touch directly, causing a sudden surge that can overheat wires or start fires.

Common electrical devices and their units of measurement are worth knowing cold, since exams love direct matching questions.

Quantity	Unit	Instrument Used to Measure
Electric current	ampere	ammeter
Voltage	volt	voltmeter
Resistance	ohm	ohmmeter/multimeter
Electrical energy (household)	kilowatt-hour (unit)	energy meter
Power	watt	wattmeter

The kilowatt-hour, the "unit" your electricity bill charges you for, is a measure of energy, not power. It represents the energy consumed by a 1,000-watt device running for one hour. A common trap question asks what a "unit" of electricity actually measures; the answer is energy consumption, not instantaneous power draw.

Static electricity is the buildup of electric charge on the surface of an object, commonly experienced when you touch a metal door handle after walking on a carpet in dry weather and feel a small shock, or when you pull a woollen sweater off and hear crackling with your hair standing up. This happens because friction between two materials transfers electrons from one surface to another, leaving one object with excess charge that discharges suddenly when it finds a conducting path, like your finger touching metal.

Conductors are materials that allow electric current to pass through easily, mainly metals like copper and aluminium, which is why electrical wiring uses these metals. Insulators resist the flow of current, such as rubber, plastic, and glass, which is why electrical wires are coated in rubber or plastic insulation and why electricians wear rubber-soled shoes and gloves for safety.

Everyday Physics Phenomena

This section covers the conceptual, non-mathematical physics that banking exams favor most, because these facts connect directly to things every reader has personally observed.

Sound is a wave that travels through the vibration of particles in a medium, air, water, or solid material. Sound cannot travel through a vacuum, since there are no particles to vibrate and carry the wave. This is why explosions in outer space, dramatic as they look in films, would actually be silent to an observer floating nearby with no medium connecting them. Sound travels fastest through solids (particles are tightly packed, transmitting vibration efficiently), slower through liquids, and slowest through gases like air, the exact opposite order of what many aspirants guess instinctively.

Light, unlike sound, is an electromagnetic wave and does not need a medium at all; it travels through the vacuum of space perfectly well, which is how sunlight reaches Earth across roughly 150 million kilometres of empty space. Light travels at approximately 3 × 10⁸ metres per second (300,000 kilometres per second) in a vacuum, the fastest speed physically possible according to established physics, and dramatically faster than sound, which travels at roughly 343 metres per second in air at room temperature. This speed gap explains a familiar experience: you see lightning instantly during a storm but hear the thunder seconds later, even though both events happen at the same moment, because light reaches your eyes almost instantaneously while sound takes noticeably longer to arrive.

Exam trap: A repeated question asks why thunder is heard after lightning is seen, despite both originating from the same event. The answer is the vast speed difference between light and sound, not that lightning happens before thunder in reality.

Reflection is when light bounces off a surface, which is how mirrors work and how you see your own image. Refraction is when light bends as it passes from one transparent medium into another of different density, such as air into water. This bending is why a straight stick partially dipped in a glass of water appears bent or broken at the water's surface, a classic everyday illustration of refraction that examiners return to often. A prism splits white light into its seven constituent colors through refraction, producing the familiar rainbow spectrum: violet, indigo, blue, green, yellow, orange, and red, commonly remembered through the acronym VIBGYOR.

Heat and temperature are related but distinct. Temperature measures how hot or cold something is, while heat is the energy that flows between objects of different temperature. Heat always flows from a hotter object to a colder one until both reach the same temperature, called thermal equilibrium, the same reason a hot cup of tea left on a table gradually cools to room temperature rather than staying hot or getting hotter on its own.

Heat transfers through three mechanisms. Conduction is heat transfer through direct contact, like a metal spoon left in hot tea becoming warm at the handle end, since heat travels through the tightly packed particles of the solid metal. Convection is heat transfer through the movement of fluid (liquid or gas), like water heating in a pot: hot water at the bottom rises while cooler water sinks, creating a circulating current that spreads heat through the whole pot. Radiation is heat transfer through electromagnetic waves that need no medium at all, which is exactly how you feel the warmth of sunlight or a bonfire from a distance, across empty space or air, without any physical contact or moving fluid.

Atmospheric pressure is the weight of the air above us pressing down, measured using a barometer. This pressure decreases as altitude increases, which is why mountaineers on very high peaks need supplemental oxygen: the air is thinner and each breath draws in fewer oxygen molecules at reduced pressure, and it is also why sealed packets of chips appear puffed up when carried to hill stations, since the lower external pressure outside the packet allows the air trapped inside to expand.

Density is mass per unit volume, and it explains why some objects float while others sink. Ice floats on water because ice is slightly less dense than liquid water, an unusual property among common substances, most of which become denser when they freeze. This is why lakes and ponds freeze from the top down, leaving liquid water beneath the ice where aquatic life can survive winter, rather than freezing solid from the bottom up.

Magnetism and electricity are deeply connected, a relationship called electromagnetism. A moving electric current creates a magnetic field around it, and a moving magnetic field can induce an electric current, the operating principle behind electric generators (motion producing electricity) and electric motors (electricity producing motion, essentially the reverse process). Every electric motor found in fans, mixers, and washing machines relies on this exact principle.

Everyday Instruments and What They Measure

Banking exams frequently test direct matching between a scientific instrument and what it measures, since these questions require pure recognition rather than calculation, making them ideal for a quick GK round.

Instrument	What It Measures
Barometer	Atmospheric pressure
Thermometer	Temperature
Ammeter	Electric current
Voltmeter	Voltage/potential difference
Speedometer	Speed of a vehicle
Odometer	Distance traveled
Hygrometer	Humidity
Seismograph	Intensity of earthquakes
Anemometer	Wind speed
Lactometer	Purity/density of milk

Memory hook: "The Weather Reporter's Toolkit." Picture a weather reporter standing on a rooftop with a full kit strapped to their belt. A barometer clipped at the waist reads air pressure. A thermometer in the shirt pocket reads temperature. A hygrometer hanging from the neck reads how sticky the air feels. An anemometer spinning on a small pole beside them catches wind speed. Every instrument on that one reporter's body has a distinct, single job, exactly like these exam questions expect you to know.

Quick Revision — One-Line Facts

• The SI unit of mass is the kilogram, not the gram.
• The SI unit of length is the metre; of time, the second.
• Scalars have only magnitude; vectors have magnitude and direction.
• Newton's first law describes inertia; the second law links force, mass, and acceleration (F = ma); the third law covers action-reaction pairs.
• Earth's gravitational acceleration is approximately 9.8 m/s².
• Friction opposes relative motion between surfaces in contact.
• Pressure is force per unit area; a sharp edge concentrates force for higher pressure.
• Work in physics requires displacement in the direction of the applied force.
• Ohm's Law: Voltage = Current × Resistance (V = IR).
• Current is measured in amperes, voltage in volts, resistance in ohms.
• In a series circuit, one failure breaks the whole loop; in a parallel circuit, other branches keep working.
• A fuse protects circuits by melting and breaking the loop during current overload.
• A kilowatt-hour is a unit of energy, not power.
• Conductors (metals like copper) allow current flow easily; insulators (rubber, plastic) resist it.
• Sound needs a medium and cannot travel through a vacuum.
• Light does not need a medium and travels through vacuum at about 3 × 10⁸ m/s.
• Lightning is seen before thunder is heard because light travels far faster than sound.
• Refraction bends light between media of different density, making a stick appear bent in water.
• A prism splits white light into seven colors, remembered as VIBGYOR.
• Heat always flows from a hotter object to a colder one until thermal equilibrium.
• Conduction needs direct contact, convection needs fluid movement, radiation needs no medium at all.
• Atmospheric pressure decreases with altitude, measured by a barometer.
• Ice floats because it is less dense than liquid water, an unusual property.
• Electromagnetism links electricity and magnetism: motion creates current (generator), current creates motion (motor).
• A barometer measures atmospheric pressure; a hygrometer measures humidity.
• An anemometer measures wind speed; a seismograph records earthquake intensity.
• A lactometer checks the purity or density of milk.
• Sound travels fastest in solids, slower in liquids, slowest in gases.
• The freezing/melting point of water at standard pressure is 0°C (273 K); the boiling point is 100°C (373 K).
• Static electricity builds up from friction transferring electrons between two surfaces.
• The Kelvin scale's zero point, absolute zero, is the theoretical temperature at which particle motion is minimal.

Memory Tables

SI Base Units at a Glance

Physical Quantity	SI Unit	Symbol
Length	metre	m
Mass	kilogram	kg
Time	second	s
Electric current	ampere	A
Temperature	kelvin	K
Amount of substance	mole	mol
Luminous intensity	candela	cd

Instruments and Their Purpose

Instrument	Measures	Everyday Example
Barometer	Atmospheric pressure	Weather forecasting
Thermometer	Temperature	Checking body/room temperature
Ammeter	Electric current	Testing circuit current draw
Voltmeter	Voltage	Checking battery output
Hygrometer	Humidity	Monitoring damp storage rooms
Anemometer	Wind speed	Airport weather stations
Seismograph	Earthquake intensity	Recording tremor magnitude
Lactometer	Milk density/purity	Dairy quality checks
Odometer	Distance traveled	Car dashboard reading

Practice MCQs

Q1. What is the SI unit of mass? (a) Gram (b) Kilogram (c) Pound (d) Newton

Q2. Which law of motion explains why passengers jerk forward when a fast-moving bus suddenly brakes? (a) Newton's first law (b) Newton's second law (c) Newton's third law (d) Law of gravitation

Q3. Which instrument is used to measure atmospheric pressure? (a) Thermometer (b) Barometer (c) Hygrometer (d) Anemometer

Q4. A "unit" of electricity billed by power companies is a measure of: (a) Power (b) Voltage (c) Energy (d) Current

Q5. In which medium does sound travel the fastest? (a) Vacuum (b) Air (c) Water (d) Solid steel

Q6. What causes a straight stick to appear bent when partially dipped in a glass of water? (a) Reflection (b) Refraction (c) Diffraction (d) Absorption

Q7. Which circuit type causes an entire string of old-style decorative lights to go dark if one bulb fails? (a) Parallel circuit (b) Series circuit (c) Short circuit (d) Open-loop circuit

Q8. Ohm's Law is expressed as: (a) P = VI (b) V = IR (c) F = ma (d) E = mc²

Q9. Why is thunder heard a few seconds after lightning is seen during a storm? (a) Thunder occurs after lightning in reality (b) Light travels far faster than sound (c) Sound travels faster than light (d) Clouds delay the sound

Q10. Which of the following best explains why ice floats on water? (a) Ice is warmer than water (b) Ice has trapped air bubbles only (c) Ice is less dense than liquid water (d) Ice has higher pressure than water

Q11. A device that melts and breaks a circuit during a current overload, protecting wiring from fire, is called a: (a) Switch (b) Fuse (c) Transformer (d) Capacitor

Q12. Which of these is a vector quantity? (a) Mass (b) Speed (c) Velocity (d) Time

Q13. Heat transfer through the actual movement of a fluid such as heated water circulating in a pot is called: (a) Conduction (b) Convection (c) Radiation (d) Insulation

Q14. VIBGYOR represents the colors produced when white light passes through a: (a) Mirror (b) Prism (c) Lens (d) Filter

Q15. According to Newton's third law, when you jump off a small stationary boat onto a riverbank, the boat: (a) Stays perfectly still (b) Moves in the same direction as you (c) Moves in the opposite direction, away from the bank (d) Sinks immediately

Answer Key

Q	Answer	Reason
1	(b) Kilogram	The SI base unit of mass is the kilogram, not the gram, despite grams being more familiar in daily use.
2	(a) Newton's first law	Inertia keeps your body moving forward even as the bus decelerates, since your motion resists sudden change without an external force acting on you directly.
3	(b) Barometer	A barometer specifically measures atmospheric pressure; a thermometer measures temperature and a hygrometer measures humidity.
4	(c) Energy	A kilowatt-hour, the billing "unit," measures total energy consumed over time, not the instantaneous rate of power draw.
5	(d) Solid steel	Sound travels fastest through solids because tightly packed particles transmit vibrations more efficiently than the loosely packed particles in liquids or gases.
6	(b) Refraction	Light bends as it passes from air into water, a denser medium, creating the visual illusion of a bent or broken stick.
7	(b) Series circuit	In a series circuit, all components share a single loop, so one broken bulb breaks the entire current path for every other bulb.
8	(b) V = IR	Ohm's Law defines voltage as the product of current and resistance, the foundational relationship for basic circuit analysis.
9	(b) Light travels far faster than sound	Both events happen simultaneously, but light at roughly 3×10⁸ m/s reaches your eyes almost instantly while sound at about 343 m/s takes measurably longer.
10	(c) Ice is less dense than liquid water	This unusual property, uncommon among substances that generally shrink and get denser on freezing, is why ice floats instead of sinking.
11	(b) Fuse	A fuse contains a thin wire designed to melt and break the circuit specifically when current exceeds a safe threshold, preventing fire or damage.
12	(c) Velocity	Velocity requires both a magnitude and a direction to be fully defined, making it a vector, unlike speed, mass, or time, which are scalars.
13	(b) Convection	Convection specifically involves the physical circulation of a heated fluid, distinct from conduction's direct contact or radiation's electromagnetic waves.
14	(b) Prism	A prism refracts and separates white light into its seven constituent wavelengths, producing the VIBGYOR spectrum.
15	(c) Moves in the opposite direction, away from the bank	Newton's third law means your forward push on the boat generates an equal and opposite reaction that pushes the boat backward.