Sunday, March 24, 2013

PPSC Past Papers of Phyics

(i)  The impedance of RLC series resonance circuit at resonant frequency is:
(a) Greater than R (b) Equal to R (c) Zero (d) None of these
(ii)  An electron has a velocity of 10km/s normal to a magnetic field of 0.1 T flux density. If the radius of the path is 569nm then the frequency is:
(a) 2.79 GHz (b) 3.1 MHz (c) 2.8 KHz (d) None of these
(iii)  If a current of 10 A flows through an electric heater for an hour and converts 8.64 MJ of electrical energy into heat energy. Then the potential difference across the heater is:
(a) 864 V (b) 240 V (c) 100 V (d) None of these
(iv)  An alpha particle is accelerated to a velocity vin a particle accelerator by a potential difference of 1200

V. Which of the following potential differenceswould be needed to double the velocity of the alpha particle?
(a) 2400 V (b) 3600 V (c) 4800 V (d) None of these
(v)  Two thin parallel wires carry currents along the same direction. The force experienced by one due to the other is:
(a) Parallel to the lines (b) perpendicular to the lines and attractive
(c) perpendicular to the lines and repulsive (d) None of these
(vi)  If 300 mA current is passing through an electric bulb, then the number of electrons passing through in one minute will be:
(a) 1.12×1020(b) 1.6×1019(c) 6.02×1018(d) None of these
(vii)  An electric iron of resistance 20 Ωtakes a current of 5.0 A. The thermal energy developed in 30s is:
(a) 15 kJ (b) 100 J (c) 10 J (d) None of these
(viii)  An ideal gas has a volume of exactly 1 liter at 1.00 atm and –20°
C. To how many atmospheres pressure must it be subjected tobe compressed to 0.500 liter at 40°C?
(a) 5.2 atm (b) 2.47 atm (c) 1.5 atm (d) None of these
(ix)  In Bohr’s model the lowest orbit corresponds to:
(a) Maximum energy (b) Minimum energy (c) Zero energy (d) None of these
(x)  The diffusion of the free electrons across the unbiased p-n junction produces:
(a) Forward bias (b) Reverse bias(c) Depletion region (d) None of these
(xi)  The P-N junction, on forward biasing acts like a:
(a) Capacitor (b) Inductor (c) Insulator (d) None of these
(xii)  The impedance at the resonant frequency of a series RLC circuits with L = 15 mH, C=0.015 F, and R = 80 Ω:
(a) 0 KΩ(b) 30 Ω(c) 80 Ω(d) None of these
(xiii)  Weber is a unit of:
(a) Magnetic field intensity (b) Magnetic Flux
(c) Magnetic Flux Density (d) None of these
(xiv)  The magnetic flux through an element of area Ain a uniform magnetic field Bis expressed as:
(a) AB (b)  B. A(c)  A x B(d) None of these
(xv)  In an electric circuit, currents flowing towards a node having fourbranches are 2A, -3A and 4A, then the current in the fourth branch is:
(a) 2A (b) -3 A (c) 4 A (d) None of these
(xvi)  With the passage of time, the rate ofdecay of a radioactive element will:
(a) Increase exponentially (b) Decrease linearly
(c) Becomes zero in two half-life time (d) None of these
(xvii)  The place where controlled fission chain reaction is carried is?
(a) A black hole (b) A star  (c) A reactor (d) None of these
(xviii) In 19thcentury, Faraday and Maxwell worked on the unification of two forces named as:
(a) Gravitational and Weak forces (b) Electric and magnetic forces
(c) Weak and Strong forces (d) None of these
(xix)  Electromagnetic wave theoryof light was proposed by:
(a) Newton (b) Michelson  (c) Maxwell (d) None of these
(xx)  The concept of field theory was put forward by:
(a) Franklin (b) Kepler  (c) Orsted (d) None of these



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