Physics in SSC CGL GK is not about solving differential equations — it is about knowing why things behave the way they do and being able to match that understanding to a four-option MCQ in under 30 seconds. The questions span a broad arc: mechanics (motion, force, rotation), heat (conduction, latent heat), electricity (power, energy, circuits), optics (reflection, refraction), and sound (wave properties). The coverage is wide but shallow — you rarely need to derive anything, but you must be precise about definitions, units, and underlying principles.
Think of the physics syllabus as a collection of conceptual anchors. Each anchor is a principle that unlocks a cluster of questions. For example, once you genuinely understand that latent heat is energy stored in a phase transition without a temperature change, a whole family of questions about steam burns, ice melting, and pressure cookers becomes trivial. Similarly, understanding that dimensional analysis is a consistency check — not a calculation — helps you identify pairs like Work and Torque that share dimensions [ML²T⁻²] without any computation.
A useful analogy: think of physics concepts as traffic signals in your city. You do not need to understand the electronics of a traffic signal to navigate the city — you need to know what red, green, and yellow mean. SSC CGL physics asks you to read the signal correctly. The "electronics" (full derivations) are for JEE, not CGL.
The recurring high-yield areas in recent papers are:
Get these six anchors solid and you cover roughly 80% of physics questions that appear in CGL GK.
Motion is classified by the path and nature of movement:
This distinction — periodic vs. oscillatory — is a live trap in recent papers (see PYQ 2024).
Force is a push or pull that changes (or tends to change) the state of rest or motion of an object. The SI unit is Newton (N).
F = ma — 1 N = the force needed to give a 1 kg mass an acceleration of 1 m/s².
Newton's three laws in exam language:
For a rigid body rotating about a fixed axis, all particles complete one full revolution in the same time T. Therefore, all particles share the same angular velocity ω = 2π/T, regardless of their distance from the axis. What differs between particles is their linear (tangential) speed: v = rω, which increases with radius r. This is why the tip of a fan blade moves faster than a point near the hub, even though both sweep the same angle per second.
Torque and Work share dimensions: Torque τ = r × F has dimensions [L][MLT⁻²] = [ML²T⁻²]. Work W = F·d has the same dimensional formula [ML²T⁻²]. They are dimensionally identical but physically distinct — Work is a scalar, Torque is a vector.
Thermal conductors vs. insulators:
Silver is the best conductor of both heat and electricity among common metals. Glass is a classic bad conductor — used in thermopane windows precisely to trap heat.
Latent heat: when a substance changes phase (solid → liquid → gas), it absorbs or releases energy without any change in temperature. This stored energy is latent heat.
Look — this is why steam at 100°C causes more severe burns than boiling water at 100°C. The water just delivers thermal energy proportional to temperature difference. The steam, on condensing, additionally releases 2260 kJ/kg. Your skin absorbs both the cooling-down energy and the condensation energy. Double damage.
Key formulas:
Power (W) = Voltage (V) × Current (A)Energy (kWh) = Power (kW) × Time (hours)For the standard "energy in units" calculation:
Energy = (Wattage ÷ 1000) × hours per day × number of days
A 60 W lamp for 5 hours a day for 30 days: (60/1000) × 5 × 30 = 0.06 × 150 = 9 kWh = 9 units. Simple arithmetic, but students routinely misplace the 1000 conversion.
Denser liquids sink; less dense liquids float on top. This is not magic — it follows directly from the definition of density (mass per unit volume). The heavier liquid per unit volume settles under gravity. This is why oil floats on water, why cream rises in milk, and why the Dead Sea lets you float effortlessly.
Archimedes' principle: a body immersed in a fluid experiences an upward (buoyant) force equal to the weight of fluid displaced. If the buoyant force equals or exceeds the body's weight, it floats.
Draw a 2×2 grid in your head: Translation (whole body shifts) | Rotation (body spins) in one row; Oscillation (back-forth, about mean) | Periodic (repeats, not necessarily back-forth) in the other. Earth around Sun = Periodic only, NOT oscillatory. Pendulum = both Oscillatory AND Periodic. Fan blades = Rotatory. Ball falling = Translatory. Checking against this 4-cell grid takes 5 seconds vs. 30 seconds of reasoning from scratch. Step count: 1 mental lookup vs. 4–5 reasoning steps.
For any "calculate units consumed" question: (1) divide Wattage by 1000 to get kW, (2) multiply by hours/day, (3) multiply by number of days. Three multiplications, no formula recall needed. For 60 W, 5 hr, 30 days: 0.06 × 5 × 30 = 9. Standard method (writing the full formula, substituting, unit conversion): ~45 seconds. This 3-step mental routine: ~12 seconds.
For thermal (and electrical) conductivity ranking among common metals — Silver, Copper, Aluminium, Gold — use the mnemonic SCAG: Silver → Copper → Aluminium → Gold (in decreasing order of conductivity). When a question asks which is the best conductor, Silver. When it asks which is the worst conductor among metals, Gold or Aluminium. Non-metals (glass, wood, air) all rank below any metal. Standard approach: trying to recall each metal's conductivity value separately (~20 seconds). SCAG recall: ~3 seconds.
Both Work and Torque are defined as Force × Distance (scalar product vs. cross product, but dimensionally the same). So [Work] = [Torque] = [ML²T⁻²]. Whenever a question asks "which two quantities share dimensions," check if both reduce to Force × Length. Power = Work/Time = [ML²T⁻³]; Moment of Inertia = [ML²]; these are different. The "Force × Distance" check eliminates wrong options in 8 seconds vs. writing out full dimensional analysis (~40 seconds).
If two substances are at the same temperature but one has undergone a phase change (steam vs. boiling water, melting ice vs. cold water), the one that just changed phase carries extra energy — the latent heat. Always pick that option when the question asks "why is X more damaging/effective." This eliminates "moves faster," "lower specific heat," or "higher temperature" as options in phase-change questions. Reduces a thermodynamics MCQ from 30+ seconds of recall to a 10-second pattern match.
When you see a Physics MCQ in the GK section, run this decision tree:
Step 1 — Identify the domain (2 seconds): Is this about motion types? Units/dimensions? Heat/conductors? Electricity calculation? Fluids/density?
Step 2 — Recall the anchor principle (5 seconds): Motion types → T-R-O-P grid. Dimensions → Force × Distance check. Conductors → SCAG ranking + non-metals below metals. Electricity → divide by 1000 then multiply. Fluids → denser sinks.
Step 3 — Eliminate first, confirm second (8 seconds): In most Physics GK MCQs, two options are clearly wrong (e.g., "moves faster" and "higher temperature" in a latent heat question). Eliminate those, then verify your anchor principle points to one of the remaining two.
Step 4 — Watch for "INCORRECT pair" format (3 seconds): These questions ask you to find the wrong example. Check each option quickly against the T-R-O-P grid or your anchor. The trap is always the option that seems plausible (Earth around Sun sounds periodic — it is, but the question may label it oscillatory, making it the incorrect pair).
Total target: under 20 seconds per physics GK question. Do not spend more than 30 seconds — move on and return.
Why this question: The most basic unit question — if you blank on this in the exam, no trick will save you. This tests whether you know the SI system cold.
Solving path: Pascal is pressure, Watt is power, Boyle is a scientist's name (not a unit at all in SI). Newton is the SI unit of force by definition: F = ma, so 1 N = 1 kg·m/s². Eliminate in 5 seconds.
Why this question: Conductor/insulator questions appear repeatedly. The trap is always "which one is the odd one out among a list of mostly metals."
Solving path: Silver, Copper, Aluminium are all metals — SCAG tells you they are good conductors. Glass is a non-metal with no free electrons. Bad conductor = Glass. 4-second SCAG lookup.
Why this question: Electricity calculation questions test the kW-hour conversion. Many candidates mess up the 1000 conversion or confuse days with hours.
Solving path: 60 W ÷ 1000 = 0.06 kW. Multiply by 5 hours/day = 0.3 kWh/day. Multiply by 30 days = 9 kWh = 9 units. Answer: 9 units. The trap option 90 units is what you get if you forget to divide by 1000. The trap option 0.3 is just one day's consumption.
Why this question: Latent heat is a recurring thermodynamics concept. The question tests whether you know why phase change matters, not just that it happens.
Solving path: Both steam and boiling water are at 100°C — so "higher temperature" is wrong. "Moves faster" and "lower specific heat" are irrelevant distractors. Steam releases latent heat of vaporization (2260 kJ/kg) on condensing — this extra energy is what causes severe burns. One-step latent heat logic.
Why this question: Rotation questions test a conceptual distinction between angular velocity (same for all particles) and linear speed (different by radius). Also a live "INCORRECT pair" format question from 2024.
Solving path: Periodic motion — Hands of a clock: correct (hands repeat every 12 hours). Rotatory — fan blades: correct (spinning about an axis). Translatory — ball falling from cliff: correct (whole body shifts). Oscillatory — Earth around the Sun: incorrect pair. Earth's revolution is periodic, not oscillatory. Oscillatory needs back-and-forth about a mean position. T-R-O-P grid check: 8 seconds.
Confusing periodic and oscillatory motion: All oscillatory motion is periodic, but not all periodic motion is oscillatory. Earth's revolution around the Sun is periodic — it is not oscillatory. Never write "oscillatory" unless there is explicit back-and-forth about a mean position.
Forgetting to divide Watts by 1000: Energy in kWh requires power in kW, not W. A 60 W lamp is 0.06 kW. Skipping the conversion gives an answer 1000 times too large — and 90 units is always listed as a trap option in exactly this kind of question.
Treating torque and work as the same physical concept because their dimensions match: They share [ML²T⁻²] but are physically distinct. Work is a scalar (dot product F·d); Torque is a vector (cross product r × F). The CGL question only asks about dimensions — do not over-extend this into saying "they are the same thing."
Ranking Gold as the best electrical/thermal conductor: Gold is excellent but Silver ranks above it. The correct order is Silver > Copper > Gold > Aluminium for conductivity. SCAG (Silver-Copper-Aluminium-Gold) is ordered by conductivity, not alphabetically — burn it in.
Assuming steam burns worse because steam is "hotter" than boiling water: Both are at 100°C. The answer is latent heat of vaporization released during condensation, not temperature difference. Options that say "higher temperature" are always wrong in this context.
Misidentifying Boyle or Pascal as units of force: Pascal (Pa) is the SI unit of pressure. Boyle is a scientist, not a unit. Newton is the only SI unit of force among standard MCQ options. Any option that is a scientist's name (Boyle, Joule, Watt) requires checking whether that name was later assigned as a unit — Joule is energy, Watt is power, Boyle is not an SI unit at all.