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۔
جب کوئی طبعی نظام جبری ارتعاشات سے گزر رہا ہو تو اسے کیا کہا جاتا ہے؟
Free harmonic oscillation
Frequency harmonic oscillation
Driven harmonic oscillator
None of these
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Explanation
Driven harmonic oscillator is a system undergoing forced vibration. In forced vibrations, an external periodic force continuously acts on the system. The system oscillates with the frequency of the applied force. This differs from free oscillations , where no external force acts. Last verified on 05-06-2026
مندرجہ ذیل میں سے کون سا فور-لیول لیزر ہے؟
ND: YAG
Ruby laser
He-Ne laser
Semiconductor laser
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Explanation
He–Ne laser is a four -level laser system. It uses a mixture of helium and neon gases as the active medium. Four-level lasers are more efficient because population inversion is easier to achieve. Ruby laser is a three - level laser. Last verified on 05-06-2026
اگر کسی جسم پر زیادہ سے زیادہ حد سے بڑھ کر تناؤ لگایا جائے اور کچھ وقت بعد ہٹا دیا جائے تو کیا ہوگا؟
The body will come back to its original position
The body will oppose the stress
The body becomes hot
The body cannot return to its original position
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Explanation
The body cannot return to its original position when stress exceeds the elastic limit. Beyond the maximum elastic value , the material undergoes permanent deformation. Even after removing the stress , the original shape is not fully recovered . This behavior is called plastic deformation . Last verified on 05-06-2026
The semi-minor axis and the time period
Eccentricity and the time period
The planet’s area of sweep and the time period
The semi-major axis and the time period
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Explanation
The semi-major axis and the time period are related by Kepler's Third Law (Law of Periods). It states that the square of a planet's orbital period is proportional to the cube of its semi-major axis. Larger orbits take longer to complete. This law helps determine planetary distances and orbital periods . Last verified on 05-06-2026
2
3
-2
0
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Explanation
"Solenoidal" means the vector field has zero divergence. No sources or sinks. For A = (x + 3y)i + (y - 2z)j + (x + mz)k
Divergence: ∇·A = ∂/∂x(Ax) + ∂/∂y(Ay) + ∂/∂z(Az)
∂/∂x (x + 3y) = 1 ∂/∂y (y - 2z) = 1 ∂/∂z (x + mz) = m So ∇·A = 1 + 1 + m = 2 + m
For solenoidal: ∇·A = 0
2 + m = 0 → m = -2
لینز کا قانون _____ کی وضاحت کرسکتا ہے؟
Only two of the three types of magnetism
Ferromagnetism only
Diamagnetism only
None of these
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Explanation
Lenz’s Law states that the induced current opposes the change that produces it .
When a magnetic field is applied, induced currents in atoms oppose the applied field .
This opposing effect explains the behavior of diamagnetic materials .
Paramagnetism and ferromagnetism are explained mainly by electron spin and magnetic domains , not Lenz’s law.
Therefore, Lenz’s Law helps explain diamagnetism only .
Last updated 13-March-2026
انسانی جسم کا اوسط اندرونی درجہ حرارت کیا ہے؟
42°C
37°C
98°C
35°C
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Explanation
The average internal temperature of the human body is 37°C (98.6°F). It is the normal body temperature range for a healthy adult.
ایک دوہری کے دوران ، _____ کے ذریعہ دوئم کے مرحلے میں تبدیلی آتی ہے؟
π⁄2 rad
π rad
2π rad
None of these
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Explanation
In one complete oscillation (one full cycle), the phase of an oscillating system changes by 2 π 2pi This corresponds to the system returning to its starting position in a periodic motion, such as simple harmonic motion.
ایک الیکٹران بجلی اور مقناطیسی میدان میں آگے بڑھ رہا ہے۔ یہ ______ سے توانائی حاصل کرے گا؟
Electric field
Magnetic field
Both of these
None of these
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Explanation
Electric Field:
An electric field exerts a force on an electron that can be in the same direction as its motion.
When this force is in the direction of motion, the electron accelerates, its speed increases, and its kinetic energy is gained from the electric field.
The work done by the electric field converts potential energy into kinetic energy.
Magnetic Field:
A magnetic field exerts a force on a moving charge that is always perpendicular to the charge's velocity.
Because this force is perpendicular to the motion, it changes the direction of the electron's motion but not its speed or kinetic energy.
Therefore, the electron does not gain energy from t he magnetic field.
لینس کی طاقت کی اکائی کیا ہے؟
Meter
Watt
Diopter
None of these
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Explanation
The power of the lens is the reciprocal of focal length .
The SI unit is dioptre .
Dioptre (D)
Power of lens = 1/ focal length in meter.
