MONDAY 1-6-2015
PHYSICS 9-11.45AM
PHYSICS 9-11.45AM
100% NABTEB 2015 Physics theory Answers
Q1
Ai.
Uniform acceleration:- A body is said to move at uniform acceleration if the rate of change of velocity with time is constant.
ii. Average speed:- is the total distance covered over the time period.
Average speed=Total distance/time taken.
2B
i. Suspend the given spiral spring vertically and attach it to scale pan and note the position of the pointer on the meter rule. Add the mass to the scale pan pointer. The valua of the difference give the total of acceleration due to gravity.
(ii) 1. Air resistance.
2. Spherical nature of the earth.
C. Draw the diagram
Velocity=time graph.
Ci. 8=v-o/30-o
8=v/30
V=8*30=240m/s.
ii. Average retadation (A)
=0-5/130/110
=-5/20
=0.25m/s.
iii. Total distance travelled during the first 50sec.
=1/2^30+240+1/2^(20*150)+(20*150)=3600+1500+3000=8100m.
V. Average speed=Total distance/Total time
8100/50=162m/s.
Q2
Ai. Dew point:- is the temperature at which the water vapour present in the atmosphere is just sufficient to saturate it.
ii. Relative humidity:-is defined as the amount of water vapour present in a given volume of air compared with mass required to saturate the same volume of air at the same temperature.
iii. Saturation vapour pressure:- is the presence exerted when a state of saturation is reached. That is when the relative humidity is 100%.
iv. Cloud:-is a condensed particle of large mass of air cooled below its dew point. Which tend to fall slowly.
(2b)
i. Specific heat capacity of water is 4200jkg^-1:- it means the amount of heat required to raise the temperature of 1kg of a substance by 1k.
ii. In tabular form gases and vapour.
Under gases
i. Respond quicker
Under vapour
Respond slowly.
Under gases
2. Equal volume expand equally.
Under vapour
equal volume expand differently
Under gases
3. Definate volume
Under vapour
Indefinate volume
Under gases
4. obtained from solid.
Under vapour
Obtained from liquid.
Q3.
A. In tabular form sound wave and radio wave.
Under sound wave
1. Travels direction of the medium is the same.
Under radio wave
Travels direction of the medium is perpendicular.
Under sound wave
3. Required material medium(mechanical)
Under radio wave
Does not required medium(electrical).
Q5.
Ai. Emission line spectra:- is when heat is applied to a given atom of substance electrons may jump from an orbit of high energy level to that of low energy level.
ii. Line absorption spectra:- when heat supplied to a given substance and he absorb it.
5B.
Draw the diagram
Ci.
1. The same amplitude and frequency.
2. Incident waves are reflected back along the incident direction.
Cii. 1. Two wave of the same frequency meet.
2. They interfere in the same phase.
iii. 1. When the critical angle is exceded.
2. Light rays pass from an optically dense medium to and optically less dense medium.
D. 1 draw the diagram
ii. Refractive index=sin c^o/sin r^o=sin(41+82)/2/sin 82/2.
Refractive index=0.8788/0.6561
Refractive index=1.34.
C.i
1 it consist of filament.
2 it can be produced by fast moving electrons hit a metal target (or anode).
ii. 1. A makes certain mineral to fluorescene.
2. It enable the structure of crystals to be obtained.
D.
i. Energy=hf.
Energy=1.6ev--10.4ev=-1.6ev+10.4ev=8.8ev
Energy=8.8*1.6*10^-19j
=14.08*10^-19j.
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