Physics
π Log in to trackSI units and instruments, laws of motion, gravitation, fluids, heat, sound, light, electricity, EM waves, nuclear physics and famous inventions. CGL asks 1-2 questions β mostly units, instruments and 'which principle explains this everyday effect'.
One page per subtopic: detailed notes, every question type, formulas, tricks and practice sets.
Every formula on one printable page, grouped by subtopic.
4 exam-level questions worked step by step.
121 questions β untimed practice or a timed test with analysis.
Track record in the exam
Questions per shift in recent SSC CGL papers.
Test difficulty mix (121 questions)
Question patterns exams keep repeating
Taken from previous-year papers. If a pattern is marked "very common", expect to see it in your exam.
SI unit of a quantity
very common"The SI unit of magnetic flux / pressure / power is..."
Learn the unit names: newton = force, joule = energy, watt = power, pascal = pressure, hertz = frequency.
Weber = magnetic flux, tesla = magnetic field. Light year is distance; kWh is energy.
What is the SI unit of magnetic flux?
Magnetic flux = field Γ area
Its unit is the weber (Wb)
Tesla is the unit of magnetic field, not flux
Weber
Instrument and what it measures
very common"Which instrument measures humidity / wind / earthquakes?"
Use the root word: hygro = moisture, baro = pressure, anemo = wind, seismo = earthquake, lacto = milk.
Which instrument measures the humidity of air?
"Hygro" means moisture
So the instrument measures moisture in air
It is the hygrometer
Hygrometer
Everyday effect and its law
very commonA daily-life effect (rocket, hydraulic brakes, floating ship) is given, with laws as options.
Match the story to the law.
Rocket or gun recoil = Newton's third law; enclosed liquid = Pascal; floating = Archimedes; fast air, low pressure = Bernoulli.
Hydraulic brakes work on which principle?
Brake fluid is enclosed in pipes
Pressure added at one end spreads equally in the liquid
A small push on the pedal gives a big force at the brakes
This is Pascal's law
Inventor or discoverer
very common"Who discovered the neutron?" or "who invented the telephone?"
Electron = Thomson, proton = Goldstein, neutron = Chadwick, nucleus = Rutherford, X-rays = RΓΆntgen.
Telephone = Bell, radio = Marconi, bulb = Edison, TV = Baird.
Who discovered the neutron?
The neutron is a particle with no charge
It sits in the nucleus
It was found in 1932 by Chadwick
James Chadwick
Eye defects and lenses
very common"Myopia is corrected by..." or "which mirror is used as a rear-view mirror?"
Myopia = concave lens. Hypermetropia = convex lens.
Rear-view mirror is convex. Shaving mirror and torch use a concave mirror.
Myopia (short-sightedness) is corrected by which lens?
In myopia the image forms in front of the retina
A diverging lens pushes it back onto the retina
A diverging lens is a concave lens
Concave lens
Simple numericals
very commonA one-step sum: lens power, parallel resistors, units of electricity, or speed conversion.
Lens power P = 1/f (f in metres). Parallel resistors: 1/R = 1/Rβ + 1/Rβ.
kWh = watts Γ hours Γ· 1000. To change km/h to m/s, multiply by 5/18.
Two resistors of 6 Ξ© and 3 Ξ© are joined in parallel. Find the equivalent resistance.
1/R = 1/6 + 1/3
= 1/6 + 2/6 = 3/6 = 1/2
So R = 2
The equivalent resistance is 2 Ξ©
Sound properties
common"Sound cannot travel through..." or "pitch depends on..."
Sound needs a medium and cannot travel in a vacuum.
Pitch depends on frequency; loudness depends on amplitude. Audible range is 20 Hz to 20 kHz.
The pitch of a sound depends on its what?
A higher frequency gives a shriller sound
So pitch follows frequency
Amplitude decides loudness, not pitch
Frequency