ASSISTANT ENGINEER ELECTRICAL PAST PAPERS YEAR 2025
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
ایک آلہ جو مکینیکل توانائی کو برقی توانائی میں تبدیل کرتا ہے اسے کیا کہا جاتا ہے؟
- Motor
- Transformer
- Coil
- Generator
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Explanation
- An electric generator is a device that converts mechanical energy into usable electrical energy.
- This process is based on the principle of electromagnetic induction.
- Discovered in 1831 by British scientist Michael Faraday.
Last verified on 27-04-2026
- 8.5 C
- 5.5 C
- 6.5 C
- None of these
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Explanation
Q = ∫[1,2] i dt = ∫[1,2] (3t² - t) dt
= [t³ - t²/2] from 1 to 2
= (2³ - 2²/2) - (1³ - 1²/2)
= (8 - 2) - (1 - 0.5)
= 6 - 0.5
= 5.5 C
- Q < 0
- Q > 1
- Q > 0
- None of these
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Explanation
Capacitors supply reactive power to the circuit, which is considered positive in standard convention.
This helps improve power factor by compensating for inductive loads.
- The movable plates half overlap the fixed plates
- The movable plates are most widely separated from the fixed plates
- Both sets of plates are exactly meshed
- None of these
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Explanation
Capacitance is maximum when the overlapping area between movable and fixed plates is greatest.
In a variable air capacitor, this occurs when the plates are fully aligned or exactly meshed.
- 5kV - 10kV
- 13kV - 30kV
- 13kV - 60kV
- None of these
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Explanation
Modern synchronous generators typically generate voltage in the range of 13 kV to 30 kV at the generator terminals.
Step-up transformers are then used to transmit this voltage efficiently over long distances.
- C = εA²/d
- C = εA/d
- C = εA/d²
- None of these
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Explanation
Capacitance is directly proportional to plate area (A) and dielectric permittivity (ε), and inversely proportional to plate separation (d).
This formula is fundamental for designing parallel-plate capacitors.
- Integral
- Log
- Exponential
- None of these
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Explanation
An op-amp integrator produces an output voltage proportional to the time integral of the input signal.
It is widely used in analog computation, waveform generation, and signal processing.
- j6
- j4
- j2
- None of these
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Explanation
If ω = 4 rad/s:
XL = j(4)(0.5)
= j2 Ω
- 15 h
- 8 h
- 10 h
- None of these
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Explanation
Rating: 50 Ah, 10 h discharge → Rated current = 50 Ah / 10 h = 5 A
Since asked current = 5 A (matches rated),
Time = Capacity / Current = 50 Ah / 5 A = 10 h
- 1 kHz
- 20 Hz
- 100 Hz
- None of these
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Explanation
f = cycles / time
= 100 cycles / 0.1 s
= 1000 Hz
= 1 kHz