SINDH PUBLIC SERVICE COMMISSION, HYDERABAD
SINDH PUBLIC SERVICE COMMISSION, HYDERABAD.
Combined Competitive Examination, 2021
P H Y S I C S.
Thursday the 17th February, 2022.
Time: 02:00 pm to 05: 00 pm Maximum marks. 100
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Note Attempt any Five questions. All questions carry equal marks.
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Question No.
01 (A) What are the mass and weight of (a) a 1420 lb snow mobile and (b) a 412 kg heat pump?
(B) What is the net force acting on a 3900 lb automobile accelerating at 13 ft/s2?
02 (A) Explain the difference between Longitudinal and Transverse waves also derive the relation for the different modes of the standing waves.
(B) Standing wave is established in a 120 cm long string fixed at both ends. The string vibrates in four segments when driven at 120 Hz (i) determine the wavelength (ii) what is the fundamental frequency.
03 (A) Explain the working principle of Carnot Engine.
(B) Determine the average value of the Kinetic Energy of the particles of an ideal gas at 00C and at 500C.
04 (A) What is the center of mass and center of gravity? How to calculate the center of mass of the different shapes? Also discuss the conservation of momentum in the system of particles.
(B) Consider a rocket at rest in empty space. What must be its mass ratio (Ratio of initial to final mass) in order that after firing its engine the rockets speed is (i) Equal to the exhaust speed and (ii) Equal to twice the exhaust speed.
05 (A) Why does the normal Zeeman effect occurs only in the atoms with an even number of electrons.
(B) Calculate the Zeeman splitting for the 3S1/2 and 2P1/2 states of sodium in the external magnetic field of 2 T.
06 (A) Discuss the deBroglie hypothesis, and also explain the Davison-Germer experiment.
(B) Explain the position-momentum and time-energy uncertainty principle.
07 (A) Describe and compare the operations of a centre-tapped full wave rectifier and bridge rectifier.
(B) Define ripple voltage and ripple factor. Calculate the ripple factor if Vr(pp) = 1.13 V and VDC = 14.3 V.
08 (A) How the paramagnets, diamagnets and ferromagnets, are classified? Also discuss Ampere’s Law in the magnetized materials.
(B) A current I flows down a long straight wire of radius R. If the wire is made of linear material with susceptibility and the current is distributed uniformly, what is the magnetic field at a distance r from the centre? Find all the bound currents. What is the net current flowing down the wire?
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