HSSC physics

Written by Dr. Hamza Farooq (Physics)

NED · طبیعیات · 25 سوالات

نام: ____________________ تاریخ: ____________

The SI unit of capacitance is the:
- A Henry
- B Coulomb
- C Farad
- D Ohm
The dimensions of force are:
- A ML⁻¹T⁻²
- B MLT⁻²
- C MLT⁻¹
- D ML²T⁻²
The momentum of a 0.5 kg body moving at 4 m/s is:
- A 8 kg m/s
- B 4.5 kg m/s
- C 0.125 kg m/s
- D 2 kg m/s
The SI unit of resistivity is the:
- A Siemens
- B Ohm per metre
- C Ohm
- D Ohm metre
Resistors of 5 Ω and 20 Ω are connected in parallel. The equivalent resistance is:
- A 4 Ω
- B 25 Ω
- C 0.25 Ω
- D 12.5 Ω
A wave has a frequency of 250 Hz and a wavelength of 1.36 m. Its speed is:
- A 184 m/s
- B 0.18 m/s
- C 340 m/s
- D 3400 m/s
An object is 30 cm from a convex lens of focal length 10 cm. The image is formed at:
- A 7.5 cm
- B 30 cm
- C 15 cm
- D 20 cm
A coil of 200 turns links a flux that changes by 0.05 Wb in 0.5 s. The induced emf is:
- A 100 V
- B 2 V
- C 10 V
- D 20 V
The heat needed to raise the temperature of 2 kg of a substance (c = 500 J/kg K) by 10 K is:
- A 1000 J
- B 10000 J
- C 5000 J
- D 20000 J
In an isothermal process on an ideal gas, the change in the internal energy is:
- A Equal to the work done
- B Negative
- C Positive
- D Zero
Light of photon energy 5 eV falls on a metal of work function 2 eV. The maximum kinetic energy of the electrons is:
- A 7 eV
- B 3 eV
- C 10 eV
- D 2.5 eV
A sample of 20 g of a radioactive substance goes through 3 half-lives. How much is left?
- A 6.7 g
- B 5 g
- C 10 g
- D 2.5 g
The force between charges of 3 μC and 4 μC placed 0.3 m apart is (k = 9 × 10⁹ N m²/C²):
- A 3.6 N
- B 12 N
- C 1.2 N
- D 0.36 N
The energy of the electron in the ground state of the hydrogen atom is:
- A −3.4 eV
- B −13.6 eV
- C 13.6 eV
- D 0 eV
Kirchhoff's first law is based on the conservation of:
- A Momentum
- B Mass
- C Energy
- D Charge
At the highest point of its path, a projectile has a vertical velocity that is:
- A Negative
- B Maximum
- C Equal to its horizontal velocity
- D Zero
A force of 10 N acts on a 2 kg body at rest through 2 m in its own direction. The kinetic energy gained is:
- A 10 J
- B 20 J
- C 40 J
- D 5 J
The time period of a simple pendulum of length 0.25 m (g = 9.8 m/s²) is about:
- A 0.5 s
- B 2 s
- C 4 s
- D 1 s
In a series RLC circuit at resonance, the impedance is equal to:
- A The inductive reactance
- B The capacitive reactance
- C The resistance
- D Zero
A force of 20 N acts at right angles to a spanner at 0.3 m from the nut. The torque is:
- A 23 N m
- B 0.015 N m
- C 60 N m
- D 6 N m
According to Gauss's law, the electric flux through a closed surface depends on:
- A The charge outside the surface
- B The charge enclosed by the surface
- C The size of the surface
- D The shape of the surface
The magnetic field near a long straight wire carrying a current varies with the distance r from the wire as:
- A 1 ÷ r
- B r
- C r²
- D 1 ÷ r²
Which of these waves does not need a medium to travel?
- A Waves on a string
- B Water waves
- C Electromagnetic waves
- D Sound waves
A rectifier is a device that changes:
- A Heat into light
- B Direct current into alternating current
- C A high voltage into a low voltage
- D Alternating current into direct current
The energy equivalent of 1 kg of mass (c = 3 × 10⁸ m/s) is:
- A 9 × 10⁸ J
- B 3 × 10⁸ J
- C 3 × 10¹⁶ J
- D 9 × 10¹⁶ J

جوابی کلید

1. C, 2. B, 3. D, 4. D, 5. A, 6. C, 7. C, 8. D, 9. B, 10. D, 11. B, 12. D, 13. C, 14. B, 15. D, 16. D, 17. B, 18. D, 19. C, 20. D, 21. B, 22. A, 23. C, 24. D, 25. D

One farad is one coulomb per volt.
Force is mass times acceleration.
Momentum = mass × velocity.
Resistivity = resistance × area ÷ length.
The value is (5 × 20) ÷ 25 = 4 Ω.
v = fλ = 250 × 1.36 = 340 m/s.
1/v = 1/10 − 1/30 = 2/30, so v = 15 cm.
emf = N × change in flux ÷ time = 200 × 0.1 = 20 V.
Q = mcΔT = 2 × 500 × 10.
The internal energy of an ideal gas depends only on its temperature.
Maximum kinetic energy = photon energy − work function.
20 ÷ 8 = 2.5 g.
F = kq₁q₂ ÷ r² = 9×10⁹ × 12×10⁻¹² ÷ 0.09 = 1.2 N.
The ground state energy of hydrogen is −13.6 eV.
The current into a junction equals the current out of it.
The vertical motion stops for an instant at the top.
By the work energy theorem the energy gained equals the work done, 10 × 2.
T = 2π√(L ÷ g) = 2π × 0.16 ≈ 1.0 s.
At resonance the reactances cancel.
Torque = force × distance = 6 N m.
The flux equals the enclosed charge divided by ε₀.
The field is B = μ₀I ÷ 2πr.
Electromagnetic waves can travel through a vacuum.
A diode rectifier lets the current pass in one direction only.
E = mc² = 9 × 10¹⁶ J.