Physics Important notes for SSC CGL / CHSL exam : GK
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Physics Important notes for SSC CGL / CHSL exam : GK
Physics Important notes for SSC CGL / CHSL exam : GK
FACTS TO REMEMBER : Important
- Speed of light is maximum in vacuum.
- Longitudinal waves can’t be polarized.
- Rainbow are always formed in direction opposite to the sun.
- The frequency of visible light varies between 400 nm to 700 nm.
- Colour blindness was first discovered by Homer (1976).
- Focal distance of tens is maximum for red light and minimum for violet fight
- 3-D Image is known as hologram.
- If a transparent material is invisible in any liquid, then both of them have the same refractive index.
- Magnifying glass is convex lens of small focal lengths’- If two mirrors are at an angle of 75° then the number of images is 5.
- Human eyes have convex lens.
- Raman Effect is related to scattering.
- Optical fibers works on the principle of total internal reflection.
- Hypo or radium thiosulphate is used for fusing in photography.
- Power of sunglass is zero.
- Heat energy are transmitted as infra-red rays.
- The first use of telescope for research was by Galeleo Galilie of Italy in 1609.
- Power measures the degree of divergence or convergence and is measured in diopetres.
- Negative sign denotes divergence or a concave lens.
- Positive sign is for convergence or a convex lens.
- Air bubble in water behaves as concave lens.
- As temperature of medium increases, its refractive index increase.
- Refractive index of a material is independent of angle of incidence.
- The angle of deviation in refractions is given by d = (i - r),i = angle of incidence and r = angle of refraction.
- 100°C = 212°F = 373 K=80R
- Bolometer is used for detection of infra-red rays.
- Specific heat of water is 1.0 calorie/gm-°C.
- Two thinner blankets are more warmer than a single blanket equal to their width.
- Colour cloths are good absorber of heat.
- Ammonia is used as a coolant in refrigerator.
- If there is a relative motion between the source and the observer, then the frequency of sound heard by the observer might be different from the frequency of the source. (Doppler's effect).
- Echo forms due to reflection of sound.
- When two sound sources of nearly same frequency are played together. then beats occur.
- Number of beats per sound equal to difference between the frequencies of sources.
- The frequency of sound produced byy supersonic engines are above audible range.
- The same note from ‘Sitar” and ‘Veena’ have different quality.
- There is a coating of iron oxide on tape used in tapere-corder.
- The pitch of sound depends upon the frequency. If n is the frequency of open organ pipe and we close an end of the organ pipe, then the frequency will be n/2
- At room temperature velocity of sound is 330 m.
- There is no change in velocity, wavelength and frequency of refractive wave.
- Audible frequency ranges from 20Hz to 20,000 Hz.
- There is no change in frequency of sound when it changes medium but its velocity, direction and intensity will be changed.
- The direction of wave is independent of velocity, wavelength and frequency.
- The velocity of sound is increased with increasing density of the medium.
- Sensation of sound is for 1/10 second.
- Receiver of telephone converts electrical energy into sound energy.
- Wave is formed by repeated vibrations of particles of medium in which the wave is formed.
- Pulse is a wave set up by single disturbance of short duration.
- The change in frequency due to Doppler’s effect is dependent on the velocities of observer and source.
- A stationary wave is characterized by the appearance of nodes and antinodes.
- There is a decrease of 2 in atomic number and decrease of 4 in mass number after emission of an a particle.
- There is an increase of 1 in atomic number after emission of a P particle.
- There is no effect of y radiation upon atomic as well as mass number.
- Neutron was discovered by Chadwick. Important physics notes by Pinnacle
- Carbon dating is used in determining age of fossils.
- Atomic mass unit (amu) is equal to — of the mass of
- 1 amu = 1.6 kg 1 amu = 931 MeV
- Binding energy is the amount of energy required to separate each nucleons from the nucleus.
- In nuclear fission, a greater nuclei is broken into smaller nuclei and there is a huge amount of energy released. Atom Bomb works on nuclear fission.
- When two or more smaller nuclei are jointed together to form a large nuclei, the process is called nuclear fusion. A great amount of energy is released. Hydrogen bomb works on principle of nuclear fusion. Nuclear fusion is the source of the Sun’s energy.
- Cadmium is a good absorber of neutrons, used as controller in atomic reaction.
- Nuclear reactor is used for controlled chain reaction.
- Heavy water. Graphite or Berilium oxide are used as moderator in nuclear reactor. (: heavy water).
- Polonium is first human made element.
- Mass of neutron is slightly greater than that of proton.
- Elements having atomic number greater than 83 must be radioactive.
- Cobalt-60 is normally used in radiation therapy.
- Before X-ray, Barium is given to the patient because Barium is good absorber of X-ray radiation.
- X-rays is used for determing structure of crystals.
- V The unit of Plank's is J/S,
- Proton is ionized hydrogen atom.
- Cryogenic engine is used in space shuttle.
- Titanium is known as metal of future.
- Uranium oxide is known as yellow cake.
- Tritium is radioactive isotopes of Hydrogen.
- Tuning of radio is an example of resonance.
- Cobalt-60 is used in Leukemia treatment
- Cybernetics is study of communication between human and machine.
- The filament of Halogen lamp is made of tungsten-iodine mixture.
- Ceramic is used in Super-conductivity.
- A transformer which increases the applied e.m.f. of an alternating current is called Step-up transformer.
- transformer, which decreases applied e.m.f. of alternating current is called step-down transformer.
- A device which convert mechanical energy into electric energy is called dynamo. However, if it produces a fairly large amount of power, it is called Generator.
- Generator is based on the principle of electromagnetic induction.
- in generator, armature consists of laminated soft iron core, from the centre of which passes a steel axle.
- Slip sings of generator are made of gun metal.
- Brushes of generator are made out of carbon or gun metal.
- Coulumb is the unit of electric charge (coulumb = ampere/second).
- 1 coulumb = 6.25
- Magnetic effect of electric current was discovered by Weston.
- Ammeter is used in DC as well as in AC. Important physics notes by Pinnacle
- Resistance of Ammeter is very low.
- Resistance of Voltmeter is very high.
- Volmeter measures potential difference between two points.
- A parallel combination of a galvanometer and a small resistance is equivalent to an ammeter.
- A series combination of a galvanometer and a high resistance is equivalent to a voltmeter.
- Ammeter is always connected in series while voltmeter is always connected in parallel.
- Electron volt is the unit of energy.
- 1 ev = 1.6J
- Watt is the unit of electric power, watt = volt x ampere =
- Kilowatt hour (KWH) is also the unit of electric power 1 KWH = 3.6 x J
- The resistance of low power (watt) bulb is high.
- Filament of electric bulb is of Tungsten.
- Wire of electric heater is made of nichrome.
- Fuse wire is made up of lead and tin.
- Transformers work on the principle of electromagnetic induction.
- A step-up transformer can convert low voltage, high frequency AC to high voltage, low frequency AC.
- A step-low transformer converts high voltage, low frequency AC to low voltage, high frequency AC.
- Transformer works on AC only.
- Transformation ratio of step-up transformer is always greater than 1.
- Ohm-meter is the unit of specific resistance.
- Lead is used in storage battery.
- Sliver is the best conductor of electricity.
- Heating effect of current doesn't depend upon the direction of current.
- AC can’t be used in electroplating.
- Soft iron is used in electric magnet.
- Preventing formation of eddy currents, laminated cores are used in transformer.
- Electric current is a continuous flow of electron.
- Capacity of battery is shown in ’Ampere-hour’.
- Chemical energy is stored in battery.
- Specific resistance of any conductor depends upon material of conductor and temperature.
- Dilute HCI is used in car battery.
- AC is not suitable for charging of storage battery.
- With increase in temperature there is decrease in resistance of Carbon, Silicon and Platinum.
- Muscovite is a common separator in electrical industries.
- Dry cell is primary cell. Important physics notes by Pinnacle
- Cadmium cell is called standard cell.
- The frequency of AC mains in India is 50HZ.
- The voltage difference of AC mains is 230V.
- The resistance of Mercury is zero at 4K.
- Copper is the most suitable for electric wire, because it has maximum number of free electrons.
- Candalescent of tube-light is always greater than that of electric bulb of the same power
1 KW = 1.34 HP
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- Mica is a common insulator in electric industries.
- Fluorine is often added to toothpaste in the form of fluoride ions.
- Both fluorine and chlorine are added to water supplies for their germicidal properties.
- Rhodium is the rarest metal.
- Helium has the lowest boiling point of any element.
- Osmium is the densest element.
- Tungsten has the highest boiling point of all the elements. Hence, it is used for filaments in electric bulbs.
- Cesium is used in atomic clocks.
- Pure silicon is a semi-conductor and is used in electronic devices as the base for minute integrated circuits (ICs).
- Mercury is the only metal which is liquid at room temperature. It is very poisonous and affects mental health.
- 1 meter distance is equal to the length of 1,650,763.73 wavelength of pure orange lights emitted from Kr-86.
- If a body is dropped vertically down, and another is projected horizontally then both will reach the ground simultaneously but with different velocity.
- The ratio to distance traveled in 1st, 2nd, and 3rd seconds of freely falling body is 1:3:5.
- The ratio of maximum height reached by different bodies projected upwards with different velocity is equal to
- If a body is dropped from top of a tower of height h and another body is thrown up simultaneously with velocity u from the foot of the tower, then both of them would meet after time h/u.
- Choke coil works on principle of electro-magnetic induction.
- If a person projected a ball outside from a moving car, then the path of the ball is a straight line for the person sitting in the car, but It should be a parabola for an observer on the ground.
- Retro-rocket is used for deceleration of rocket in space.
- The shape of rain drop is spherical due to surface tension.
- Goniometer is used in determining angle of
- Lactometer is used to determining purity of milk.
- The height of mercury column in barometer is independent of the diameter of glass-tube containing mercury.
- The frequency of second pendulum is 2s.
- Clouds are flying due to their least density and viscosity of air.
- Viscosity of gases increases with increase in temperature.
- The force of attraction between atoms of the same material is called cohesive force.
- The force of attraction between atoms of different material is called adhesive force.