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۔
فیوجن ری ایکٹر میں نیوکلیائی ذرات کے درمیان الیکٹرو اسٹیٹک ریپلسن کو ختم کرنے کے لیے کیا ضروری ہوتا ہے؟
- Very high pressure
- Very high temperature
- Very small volume
- All of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- In a fusion reactor, nuclei must overcome strong electrostatic (Coulomb) repulsion.
- To achieve fusion, extremely high energy conditions are required.
- Very high temperature gives nuclei enough kinetic energy to approach each other.
- Very high pressure and very small volume increase collision probability.
Last verified on 05-06-2026
زینر ڈائیوڈ کی بہترین وضاحت کیا ہے؟
- It operates in reverse region
- It is a constant voltage device
- It is a constant current device
- All of these
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Explanation
- Zener diode is mainly used as a constant voltage regulator.
- It operates in the reverse breakdown region.
- In this region, voltage remains almost constant even if current changes.
Last verified on 05-06-2026
جب دو چارجز کے درمیان ہوا میں فاصلہ ہو اور ان کے درمیان ڈائی الیکٹرک شیٹ رکھ دی جائے تو ان کے درمیان برقی قوت پر کیا اثر ہوگا؟
- Decrease
- Increase
- Remain unchanged
- Become zero
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Explanation
When a dielectric is placed between two charges, the electrostatic force decreases.Dielectric materials get polarized in an electric field.
This polarization reduces the effective electric field between charges.
Hence, the force between charges becomes weaker than in air.
Last verified on 05-06-2026
- Number of electrons increases while that of holes decreases
- Number of holes increases while that of electrons decreases
- Number of electrons and holes remain same
- Number of electron and holes increases equally
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Explanation
- When an N-type semiconductor is heated, thermal energy generates electron–hole pairs.
- The number of electrons increases in the conduction band.
- At the same time, equal number of holes are created in the valence band.
- Doping does not change this thermal generation behavior.
Last verified on 05-06-2026
جب ایک الیکٹرک ڈائپول پر الیکٹرک فیلڈ ٹارک پیدا کرتا ہے تو یہ کس حالت میں ہوتا ہے؟
- The field is parallel to the dipole moment
- The field is negative
- The field is perpendicular to the dipole moment
- The field is positive
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Explanation
- A torque acts on an electric dipole in an external electric field.
- Torque depends on the angle between dipole moment and electric field.
- Maximum torque occurs when the field is perpendicular to the dipole moment.
- If the field is parallel, torque becomes zero.
Last verified on 05-06-2026
مندرجہ ذیل میں سے کس حالت میں نیٹ الیکٹرک فیلڈ صفر ہوتا ہے؟
- Inside any conductor
- Inside any conductor with a static charge
- Inside any material, conductor or insulator, with a static charge
- The electric field cannot be zero
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Explanation
- Net electric field inside a conductor in electrostatic equilibrium is zero.
- Free electrons in a conductor rearrange themselves until internal field cancels out.
- This condition holds when the conductor is in a static (electrostatic) state.
- Inside insulators, electric field is generally not zero.
Last verified on 05-06-2026
الفا پارٹیکل کی وہ اوسط دوری جو وہ ہوا میں طے کرتا ہے جب تک اس کی آئنائزنگ طاقت ختم نہ ہو جائے، اسے کیا کہتے ہیں؟
- Trajectory
- Range
- Firing level
- Limit
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Explanation
- The average distance covered by an alpha particle in air before losing its ionizing power is called its range.
- Alpha particles lose energy continuously while moving through air.
- They stop ionizing after traveling a certain distance.
- This stopping distance is not straight-line path always due to collisions.
Last verified on 05-06-2026
نیوکلیئر ری ایکٹر میں مندرجہ ذیل میں سے کون سا صحیح بیان ہے؟
- Moderator slow down the neutron
- Moderator bring the neutrons to rest
- Moderator absorb the neutron
- Moderator reflect the neutron
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Explanation
- In a nuclear reactor, a moderator slows down fast neutrons.
- Slow (thermal) neutrons are more effective in sustaining fission.
- Moderators do not stop, absorb, or reflect neutrons completely.
- Common moderators are graphite and heavy water.
Last verified on 05-06-2026
ہائیڈروجن اسپیکٹرم کی کون سی سیریز الٹرا وائلٹ ریجن میں پائی جاتی ہے؟
- Lyman series
- Balmer series
- Paschen series
- Bracket series
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Explanation
- Lyman series lies in the ultraviolet (UV) region of hydrogen spectrum.
- It is produced when an electron falls to the first energy level (n = 1).
- These transitions release high-energy photons.
Additional information:
- Balmer series lies in the visible region.
- Paschen and Brackett are in infrared.
Last verified on 05-06-2026
جب مناسب فریکوئنسی کی روشنی دھات کی سطح پر پڑتی ہے تو الیکٹران خارج ہوتے ہیں، اس عمل کو کیا کہتے ہیں؟
- X-ray emission
- Compton effect
- Nuclear fission
- Photoelectric effect
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Explanation
- Photoelectric effect is the phenomenon where electrons are ejected from a metal surface.
- It occurs when light of suitable frequency falls on the metal.
- The incident photons transfer energy to electrons.
- If energy is sufficient, electrons are emitted from the surface.
Last verified on 05-06-2026