SPSC LECTURER PHYSICS PAST PAPER 20-01-2025
Lecturer Physics 5 years Past Papers Click Here
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
وین کی نقل مکانی کا قانون ______ ہے؟
𝜆𝑚𝑇= constant
𝜈𝑚𝑇= constant
ν𝜆𝑚 = constant
None of these
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Explanation
Wien's Displacement Law states that the product of the wavelength at which a blackbody emits maximum intensity ( λ m lambda_m ) and its absolute temperature ( T T ) is constant: λ m T = constant lambda_m T = text{constant} . It explains the inverse relationship between temperature and peak wavelength . It meaning hotter objects emit radiation at shorter wavelengths.
3
4
6
None of these
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Explanation
The energy required to excite an electron from the second orbit to the third orbit is:
ΔE = 13.6Z^2(1/4 - 1/9) eV
Given ΔE = 42.7 eV:
42.7 = 13.6Z^2(1/4 - 1/9)
Solving for Z:
Z = 4
4
6
8
None of these
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Explanation
The splitting in a magnetic field is determined by the formula 2 j + 1 2j + 1 , where j j is the total angular momentum quantum number. For 2 D 1 / 2 2D_{1/2} , j = 1 / 2 j = 1/2 , so the number of components is 2 ( 1 / 2 ) + 1 = 6.
انڈکٹنس کے ذریعے کرنٹ ______ کی پیروی کرتا ہے؟
An exponential growth
A linear growth
A linear decay
None of these
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Explanation
When current flows through an inductance , it builds up gradually due to the back electromotive force (EMF) induced by the changing current.
This results in an exponential growth of the current over time.
3 Hz
1 Hz
2 Hz
None of these
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Explanation
To find the frequency, we can use the equation:
v_max = A * ω
where v_max = 31.4 cm/s, A = 5 cm
ω = v_max / A
= 31.4 cm/s / 5 cm
= 6.28 rad/s
Now, ω = 2 * π * f
f = ω / (2 * π)
= 6.28 rad/s / (2 * π)
= 1 Hz
9600A˚
19200A˚
4800A˚
None of these
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Explanation
Using Wien's displacement law:
λ_peak ∝ 1/T
Given: Initial temperature (T1) = 6000 K, Initial peak wavelength (λ1) = 4800 Å
Final temperature (T2) = 3000 K
λ2 / λ1 = T1 / T2
λ2 = λ1 * T1 / T2
= 4800 Å * 6000 K / 3000 K
= 9600 Å
Increase to 150 N
Remains at 75 N
Decrease
None of these
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Explanation
Since the two boxes are identical , the weight of the second box is equal to the weight of the first box.
The normal force from the table will increase to support the combined weight of both boxes, which is 150 N (2 x 75 N).
0.33
0.03
0.3
None of these
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Explanation
According to Kirchhoff's law:
Coefficient of emission (e) + Coefficient of reflection (r) + Coefficient of transmission (t) = 1
Given: t = 0.33, r = 0.64
e + 0.64 + 0.33 = 1
e = 1 - 0.97
= 0.03
بوسنز میں سڈول لہر کے افعال ہوتے ہیں۔ وہ نہیں مانتے ______؟
Hund’s Rule of Maximum Multiplicity
Aufbau principle
Pauli’s Exclusion Principle
None of these
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Explanation
Bosons have symmetrical wave functions and can occupy the same quantum state without restriction. The Pauli Exclusion Principle applies only to fermions, which have antisymmetric wave functions and cannot share the same quantum state.
8 x 10^6 Hz
8 x 10^8 Hz
8 x 10^4 Hz
None of these
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Explanation
Using the Heisenberg Uncertainty Principle:
ΔE * Δt >= h/4π
where ΔE = h * Δv (energy uncertainty) and Δt = 10^(-8) s (lifetime)
h * Δv * 10^(-8) >= h/4π
Δv >= 1/(4π * 10^(-8))
≈ 8 x 10^6 Hz
