SPSC LECTURER PHYSICS PAST PAPERS 2000 TO TILL DATE
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
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 .
4.5 × 10^7 m/s
5.5 × 10^7 m/s
8.5 × 10^10 m/s
None of these
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Explanation
Using the relativistic mass equation: m = m0 / sqrt(1 - v^2/c^2)
Rearranging to solve for v:
v ≈ sqrt(1 - (m0/m)^2) × c
Plugging in the values:
v ≈ sqrt(1 - (60/61)^2) × 3.0 × 10^8 m/s
≈ 4.5 × 10^7 m/s
کلاسیکی تھیوری کے مطابق داڑھ کی مخصوص حرارت کی قدر _____ ہے؟
R
2R
3R
None of these
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Explanation
According to the classical equipartition theorem , the molar specific heat at constant volume (Cv) : for a monatomic gas is (3/2)R for a diatomic gas is (5/2)R for a solid is 3R (Dulong-Petit law). The molar specific heat at constant pressure (Cp) for a solid is approximately 3R .
بریگ کی مساوات _____ کا نتیجہ ہے؟
Diamond structure
Schrodinger equation
Laue equations
None of these
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Explanation
Bragg's equation (nλ = 2d sinθ) is derived from Laue equations . It describe the diffraction of X-rays by crystal lattices. Max von Laue formulated these equations, which later led to Bragg's Law , explaining X-ray diffraction patterns.
0.5 × 10^-4 kgm^2
0.5 kgm^2
0.5 × 10^4 kgm^2
None of these
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Explanation
To find the moment of inertia (I) of the rotating body, we can use the formula:
τ = I × α
where τ is the torque, I is the moment of inertia, and α is the angular acceleration.
Given:
τ = 2 × 10^-4 Nm
α = 4 rad/s^2
Rearranging the formula to solve for I:
I = τ / α
= (2 × 10^-4 Nm) / (4 rad/s^2)
= 0.5 × 10^-4 kgm^2
کوانٹم نمبر _____ کے حل ہیں؟
Einstein's mass energy relation
Schrodinger's Wave Equation
Hamilton Operator
None of these
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Explanation
Quantum numbers arise as solutions to Schrödinger's wave equation . It describes the behavior of electrons in an atom. These numbers define electron properties like energy levels (n), shape (l), orientation (mₗ), and spin (mₛ).
4.5 × 10^10
4.5 × 10^9
9 × 10^9 years
None of these
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Explanation
To find the time it takes to decay 75% of the initial amount, we need to find the time it takes for 25% of the initial amount to remain.
Since the half-life is 4.5 × 10^9 years, after one half-life, 50% of the initial amount remains.
After two half-lives, 25% of the initial amount remains (50% of 50%).
Therefore, the time it takes to decay 75% of the initial amount is:
2 × half-life = 2 × 4.5 × 10^9 years = 9 × 10^9 years
