SPSC PHYSICS 25 YEARS PAST PAPERS
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
ایک جہتی آسکیلیٹرز کی اوسط توانائی کے لئے کلاسیکی اظہار ہے؟
(3/2 KBT)
(1/2 KBT)
(KBT/2 + KBT/2)
None of these
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Explanation
The classical expression for the mean energy of a one-dimensional oscillator is: (1/2 KBT) + (1/2 KBT)
= KBT
0.048
0.768
0.003
None of these
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Explanation
The average translational kinetic energy of a molecule is given by:
(3/2)kT = (3/2) × (1.38 × 10^-23 J/K) × T
Since the temperature is the same for both O2 and N2 molecules , the average translational kinetic energy will be the same:
0.048 eV = (3/2)kT
The mass of the molecule does not affect the average translational kinetic energy .
Therefore, the translational kinetic energy of N2 molecules at the same temperature is also:
0.048 eV
ویکیوم یا خالی جگہ ، کون سے مشاہدات کیے جاتے ہیں؟
p = 0, J = 0
p = po, J = 0
p = 0, J = J
None of these
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Explanation
In a vacuum or free space, there are no particles or matter, so:
Pressure (p) is zero . Current density (J) is also zero , since there are no charged particles to carry current. Therefore, the correct observation is p = 0, J = 0.
0.26 m
0.36 m
0.83
None of these
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Explanation
1/f = 1/v - 1/u
2.5 = 1/0.75 - 1/u
u = -0.26 m
So, the new near point is indeed:
0.26 m
کسی سیارے کے بڑے پیمانے پر اور قطر زمین سے دوگنا ہوتا ہے۔ پینڈولم سیارے کے دوچار ہونے کی مدت ہوگی (اگر یہ زمین پر دوسرا لاکٹ ہے)؟
2√2 seconds
1√2 seconds
1/2 second
None of these
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Explanation
The formula for the period of a pendulum is T = 2π√(l/g) , where l is the length of the pendulum and g is the acceleration due to gravity. Since the mass and diameter are doubled , the acceleration due to gravity (g) on the planet will be half that of Earth. Therefore, the new period of oscillation will be √2 times the period on Earth, meaning if it was a second's pendulum on Earth, it will be 2√2 seconds on the planet.
275K
325K
250K
None of these
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Explanation
Initial efficiency (η) = 40% = 0.4
Sink temperature (Tc) = 300 K
Initial source temperature (Th) = 300 / (1 - 0.4) = 500 K
New efficiency (η_new) = 0.4 + 0.5(0.4) = 0.6
New source temperature (Th_new) = 300 / (1 - 0.6) = 750 K
Increase in temperature = Th_new - Th = 750 - 500 = 250 K
ایک ڈوپول میں ، گاؤس تھیوریم کی قیمت _____ ہوگی؟
2
1
0
None of these
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Explanation
Gauss's Theorem (Gauss's Law) : States that the total electric flux through a closed surface is proportional to the enclosed charge. Dipole Net Charge : A dipole consists of equal and opposite charges (+q and -q). So the net charge enclosed by any Gaussian surface around it is zero . This making the Gauss theorem value 0 .
50°
30°
40°
None of these
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Explanation
Since μ = 1/√3, we can use the fact that μ = tan(θ) when the block just slides down the inclined plane.
μ = 1/√3 = tan(θ)
θ = arctan(1/√3)
θ = 30°
2.05 MeV
4.1 MeV
1.02 MeV
None of these
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Explanation
Given:
Energy of photon (E) = 4.1 MeV
The total energy available for the electron and positron is:
E - 2 × 0.511 MeV = 4.1 MeV - 1.022 MeV = 3.078 MeV
Since the electron and positron share the energy equally, the kinetic energy of the electron is:
3.078 MeV / 2 = 1.539 MeV
Adding the rest mass energy of the electron (0.511 MeV), we get:
Energy of electron = 1.539 MeV + 0.511 MeV = 2.05 MeV
ایک مساوی پرزم اور ہوا کا 45 ڈگری کا نازک زاویہ ہوتا ہے۔ اگر آنے والی شعاع ریفریکٹنگ سطح پر کھڑی ہے تو یہ _____؟
It keeps reflecting from all the three sides of the prism and never emerges out
It gets reflected from second and third surfaces and emerges from the first surface
It is reflected from the second surface and emerges perpendicular from the third surface
None of these
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Explanation
Total Internal Reflection (TIR) : Since the critical angle is 45° , and the incident ray is perpendicular to the first surface , it enters without deviation and strikes the second surface at 60° (greater than 45°), causing TIR . Emergence : After reflecting from the second surface, the ray reaches the third surface at 30° , which is less than the critical angle , so it emerges perpendicularly from the third surface .
