1- Helium has the lowest boiling point of any element.
2- Osmium is the densest element.
3- Tungsten has the highest boiling point of all the elements. Hence, it is used for filaments in electric
4- Cesium is used in atomic clocks.
5- Pure silicon is a semi-conductor and is used in electronic devices as the base for minute integrated circuits (ICs).
6- Mercury is the only metal which is liquid at room temperature. It is very poisonous and affects mental
7- 1 meter distance is equal to the length of 1,650,763.73 wavelength of pure orange lights emitted from Kr-86.
8- If a body is dropped vertically down, and another is projected horizontally then both will reach the ground simultaneously but with different velocity.
9- The ratio to distance traveled in 1st, 2nd, and 3rd seconds of freely falling body is 1:3:5.
10- The ratio of maximum height reached by different bodies projected upwards with different velocity is equal to
11- 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.
12- Choke coil works on principle of electro-magnetic induction.
13- 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.
14- Retro-rocket is used for deceleration of rocket in space.
15- The shape of rain drop is spherical due to surface tension.
16- Goniometer is used in determining angle of
17- Lactometer is used to determining purity of milk.
18- The height of mercury column in barometer is independent of the diameter of glass-tube containing
19- The frequency of second pendulum is 2s.
20- Clouds are flying due to their least density and viscosity of air.
21- Viscosity of gases increases with increase in temperature.
22- The force of attraction between atoms of the same material is called cohesive force.
23- The force of attraction between atoms of different material is called adhesive force
.
24- Candalescent of tube-light is always greater than that of electric bulb of the same power
24- Candalescent of tube-light is always greater than that of electric bulb of the same power
25- 1 KW = 1.34 HP
26 -Tritium is radioactive isotopes of Hydrogen.
27-Tuning of radio is an example of resonance.
28-Cobalt-60 is used in Leukemia treatment
29-Cybernetics is study of communication between human and machine.
30-The filament of Halogen lamp is made of tungsten-iodine mixture.
31-Ceramic is used in Super-conductivity.
32-A transformer which increases the applied e.m.f. of an alternating current is called Step-up transformer.
33-Transformer, which decreases applied e.m.f. of alternating current is called step-down transformer.
34-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.
35-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.
36-Slip sings of generator are made of gun metal.
37-Brushes of generator are made out of carbon or gun metal.
38-Coulumb is the unit of electric charge (coulumb = ampere/second).
39-1 coulumb = 6.25
40-Magnetic effect of electric current was discovered by Weston.
41-Ammeter is used in DC as well as in AC.
42-Resistance of Ammeter is very low.
43-Resistance of Voltmeter is very high.
44-Volmeter measures potential difference between two points.
45-A parallel combination of a galvanometer and a small resistance is equivalent to an ammeter.
46-A series combination of a galvanometer and a high resistance is equivalent to a voltmeter.
47-Ammeter is always connected in series while voltmeter is always connected in parallel.
48-Electron volt is the unit of energy.
49-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
50-The resistance of low power (watt) bulb is high
51. Speed of light is maximum in vacuum.
52. Longitudinal waves can’t be polarized.
53. Rainbow are always formed in direction opposite to the sun.
54. The frequency of visible light varies between 400 nm to 700 nm.
55. Colour blindness was first discovered by Homer (1976).
56. Focal distance of tens is maximum for red light and minimum for violet fight
57. 3-D Image is known as hologram.
58. If a transparent material is invisible in any liquid, then both of them have the same refractive index.
59. 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.
60.Human eyes have convex lens.
61.Raman Effect is related to scattering.
62.Optical fibers works on the principle of total internal reflection.
63.Hypo or radium thiosulphate is used for fusing in photography.
64.Power of sunglass is zero.
65.Heat energy are transmitted as infra-red rays.
66.The first use of telescope for research was by Galeleo Galilie of Italy in 1609.
67.Power measures the degree of divergence or convergence and is measured in diopetres.
68.Negative sign denotes divergence or a concave lens. v Positive sign is for convergence or a convex lens.
69.Air bubble in water behaves as concave lens.
70.As temperature of medium increases, its refractive index increase.
71.Refractive index of a material is independent of angle of incidence.
72.Ammonia is used as a coolant in refrigerator.
73.100°C = 212,°F = 373, K=80R
74.Bolometer is used for detection of infra-red rays.
75.Specific heat of water is 1.0 calorie/gm-°C.
No comments:
Post a Comment