# PPSC Lecturer Physics Key Points 2017 Must Prepare Now

PPSC Lecturer Physics Key Points 2017 Must Prepare Now

1.Value of “g” remains constant in the range of 1km.
2.Area under v-t graph gave distance.
3. Fnet=0 , ∆a=0 , ∆v does not equal to zero. The body will move with constant velocity.
4. When a triangle have two sides equal then there angle will also be equal.
5.increase in K.E=4 times
Momentum=?
P=√2mE
P= 2 times
6. Every declaration is not retardation acceleration but every retardation acceleration is deceleration.
7. Rocket propulsion involved Newton’s 3rd law of Motion.
8. In Equation of motion , the acceleration is uniform.
9. One second is defined as 9192631770 periods of Cesium clock.
10. The magnitude of dot product and cross product will be same at 45° and 225°.
11. In stationary wave pressure is maximum at node and minimum at anti-node.
12. For Resonance;
i- Amplitude large
ii- Frequencies match
iii- Response must
13. Speed of sound in ;
i- solid 5000m/S
ii- liquid 1500m/s
iii- Gas 332m/s and vacuum zero.
14.Sound waves cannot be polarized because they are Longitudinal Waves.
15. Human ear can listen
20Hz-20000Hz
Infrasonic< 20Hz and 20000Hz<Ultrasonic
16. Same medium. Different medium
V=f x lambda. V= f x lambda
V remains constant. f remains constant.
Diffraction. Refraction
17. Speed of sound depends upon;
i- pressure
ii- increase in temp
iii- molecular weight
18. The wave which start from extreme position called cosine wave.
19. Sine wave starts from mean position.
20. Pyrometer used to measure pressure and Barometer used for high and low pressure.
21. For a satellite orbiting around earth P.E is greater than K.E.
22. Dyrometer:- Energy measurements.
23… directly proportional to moment of inertia.
24. Acceleration describes path motion followed by body.
25.No. Of beats per second= Diff of frequencies (beats)
26. S.H.M is a type rectilinear motion.
27. Linear Magnification
M= infinite
28. Resolving power inversely proportional to wavelength and directly proportional to Diameter.
29. In YDSE wave front divided.
30. Distance b/w object and its real image formed by convex lens cannot be less than 4f.
31. At the point if contact of lens and glass plate thickness is zero.
That’s why Newton’s centre is dark.
32. When object is placed B/w principle axis and focus image is erect, virtual and enlarge.
33. Focal length of directly proportional to wavelength means maxi for red and mini for violet.
34. The reason of seeing sun earlier of sunrise is refraction of light.
35. Rainbow form due to dispersion and total internal reflection combination.
36. When water heat
0° – 4° volume decrease
5°- 100° volume increases.
37. CNG engine efficiency= 18%
Petrol engine=25%
Diesel engine =40-45%
38.change in entropy in adiabatic is zero.
39. We cannot see through the fog due to scattering.
40. Scattering inversely proportional to wavelength.
41. Response for yellow-green light human eye is 5500A°.
42. Intensity becomes half after polarization.
43. Stars seems twinkle due to different refractive index in atmosphere of earth.
44. Newton’s rings formed due to interference.
45.total internal reflection conditions;
i- Denser to rare.
ii- incidence angle > critical angle.
46.Entropy of gases is greater than the solids.
47. Real gases can obey gas law for
High temp and low pressure.
Part 2
1. When electrons removed from neutral metal electric charge on it is +1.6C.
2. Metal cannot be used as electric medium B/w plates of capacitor.
3. A charged conductor has charge on its outer surface.
4. Glass has loosely bounded electrons.
5. Glass used B/w parallel plate capacitor to increase capacitance.
6. Work done in carrying a unit charge b/w two points on an equipotential is zero.
7. Flux density is a vector quantity.
8. Tensor is a quantity which have different values in different directions.
9. Mass of Alpha particle is 4 times of mass of proton.
10. Charge on alpha particle is 2 times of proton.
11. A device is non ohmic its resistance is dynamic.
12. A hollow charged surface does not produce E at internal.
13.when supply us given to a transfer its output voltage is zero volt.
14. The electrical circuit used to got smooth D.C output for a rectifier is called Filter.
15. A hot body will radiate maxi energy if its surface is Black and rough.
16. Diode can’t perform amplification because it is a two terminal device.
17. A choke coil have high inductance and low resistance. It control current due to Lenz’s law.
18. The value of A.C produces heat is called virtual value.(Ch # 16 article before three phase)
19. In Hysteresis magnetizing current leads the magnetism.
20. Potential drop not depend upon temp.
21. A fast reactor does not use a moderator. i.e Uranium does not need a moderator.
22. Lyman series lies in both absorption and emissions.
23. Compound micro scope theory explained by liquid drop theory.
24. Fusion reaction is a source of energy in Hydrogen bomb and sun.
25. Fission reaction produces energy 0.9MeV per nucleon.
26. Fusion reaction produces energy 6MeV per nucleon.
27. A photon is always considers to moving with speed of light.
28. Leptrons are electron , neutrino and anti-neutrino.
29. Proton and neutron are called nucleon.
30. The meaning of negative energy in a system indicate Bound energy.
31. Gamma particles are more penetrating but alpha are most dangerous for body.
32. Entering Flux is +ve and outgoing flux is -ve.
33. Ohm’s law is only applicable to conductors.
34. Drift velocity cannot be increased by temp.
35. Magnetic field toward reader shows by X(outward).
36. Because of ionization of salt conductivity increases
37. Current obtained by generator is displacement current.
38. The conductivity of super conductor is infinite.
39. Energy stored in chook coil in the form of magnetic energy.
40. The best materiel for core of transformer is soft iron.
41. The energy produced in fusion reaction is 6 times more than a fission reaction.
42. Fusion takes place on earth only in Hydrogen bomb.
43. An op-amp consists of total 5 terminals.
44. Neutrons are more damaging for eyes.
45. Laser is used in micro surgery.
46.Fission reaction was discovered by two German scientists who Ottottann and Strassman in
1939.
47. Einstein photoelectric effect base upon conservation of mass.
48. Nuclear forces are short range and charge independent.
49. Penetrating power of X-rays can be increased by frequency.
50. D.C have zero Frequency.
51. Good materiel for making Electro magnet is Iron.
52. Admittance is reciprocal of impedance.

PPSC Lecturer Physics Key Points 2017 Must Prepare Now