UET Lahore ECAT Physics: Practice MCQs with Answers

UET Lahore ECAT Physics Practice sample MCQs

1. Q1. The current in an AC circuit is given by I = 10 sin(100t). The frequency is

   • A) 50 / π Hz
   • B) 100 / (2π) Hz
   • C) 50 Hz
   • D) 100 Hz

   Answer: 50 / π Hz

2. Q2. A series LCR circuit has R = 10 ohm, L = 0.1 H, and C = 100 μF. If the frequency of the AC source is 50 Hz, what is the impedance?

   • A) 17.9 ohm
   • B) 14.1 ohm
   • C) 20 ohm
   • D) 10 ohm

   Answer: 10 ohm

3. Q3. In an AC circuit, the voltage is given by V = 200 sin(100πt) and the current is given by I = 10 sin(100πt + π/3). What is the power factor?

   • A) 0.5
   • B) 0.866
   • C) 1
   • D) 0

   Answer: 0.5

4. Q4. A circular coil of radius 0.1 m is placed in a uniform magnetic field of 0.2 T. If it's rotated by 180° in 0.2 s, find induced emf.

   • A) 0.0628 V
   • B) 0.1256 V
   • C) 0.628 V
   • D) 1.256 V

   Answer: 0.0628 V

5. Q5. A coil is rotated in a magnetic field. The emf induced is maximum when the coil is

   • A) parallel to the field
   • B) perpendicular to the field
   • C) at 45° to the field
   • D) at 60° to the field

   Answer: parallel to the field

6. Q6. A thermodynamic system undergoes a process in which its internal energy decreases by 500 J. If the work done by the system is 750 J, the heat transferred to the system is

   • A) -1250 J
   • B) 250 J
   • C) -250 J
   • D) 1250 J

   Answer: 250 J

7. Q7. A spring has a spring constant of 100 N/m. What is the work done in compressing it by 2 m?

   • A) 100 J
   • B) 200 J
   • C) 2000 J
   • D) 400 J

   Answer: 200 J

8. Q8. A 10 V battery is connected to a 5 ohm resistor. The current is

   • A) 1 A
   • B) 2 A
   • C) 0.5 A
   • D) 5 A

   Answer: 2 A

9. Q9. The impedance of an LCR circuit at resonance is

   • A) R
   • B) L
   • C) C
   • D) 1/R

   Answer: R

10. Q10. The unit of electric flux is

    • A) N m² / C
    • B) N / C
    • C) V m
    • D) V / m

    Answer: N m² / C

11. Q11. The ratio of specific heats (Cp/Cv) for a diatomic gas is

    • A) 1.67
    • B) 1.4
    • C) 1.3
    • D) 1.2

    Answer: 1.4

12. Q12. How many significant figures in 100.0?

    • A) 1
    • B) 2
    • C) 3
    • D) 4

    Answer: 4

13. Q13. What is the dimension of velocity?

    • A) LT⁻¹
    • B) LT²
    • C) L²T
    • D) L⁻¹T

    Answer: LT⁻¹

14. Q14. Absolute error in the above measurements?

    • A) 0.005
    • B) 0.01
    • C) 0.02
    • D) 0.03

    Answer: 0.01

15. Q15. The power dissipated in a 10 ohm resistor is 40W. What is the current?

    • A) 1 A
    • B) 2 A
    • C) 4 A
    • D) 8 A

    Answer: 2 A

16. Q16. A mass-spring system has a time period of 2 s. What is its frequency?

    • A) 0.5 Hz
    • B) 1 Hz
    • C) 2 Hz
    • D) 4 Hz

    Answer: 0.5 Hz

17. Q17. A series LCR circuit is in resonance. What is the impedance of the circuit?

    • A) R
    • B) L
    • C) C
    • D) L + C

    Answer: R

18. Q18. What are the dimensions of force?

    • A) MLT⁻²
    • B) ML²T⁻²
    • C) MLT⁻¹
    • D) ML²T⁻¹

    Answer: MLT⁻²

19. Q19. In an AC circuit, the voltage and current are given by V = 200 sin(100πt) V and I = 5 sin(100πt - π/3) A. The power loss is

    • A) 500 W
    • B) 250 W
    • C) 1000 W
    • D) 750 W

    Answer: 250 W

20. Q20. The impedance of an AC circuit is given by Z = √(R² + X²), where X is the reactance. For a capacitor, X is

    • A) 1 / ωC
    • B) ωC
    • C) ωL
    • D) 1 / ωL

    Answer: 1 / ωC

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