Federal Board HSSC-II (2012)
PHYSICS
Time: 25 Minute
Marks: 17
SECTION A

Q. 1 Circle the correct option i.e. A/B/C/ D. Each part carries one mark.

• The fact that Electric Field exists in space around an electrical charge is_______   
  

(A) Electrical property
(B) Gravitational Field
(C) Intrinsic property of nature
(A) All of these

• One coulomb charge is carried by
  

(A) 6.25 x10¹⁸
(B) One electron
(C) 1.6 x10^-19
(D) None of these

• Power of an electric generator of voltage (v) and driving current (I) through an appliance is.
  

(A) P= VI                                                   
(B) P = I²R
(C) P = 
(D) All of these

• Electric field and potential difference inside a hollow charge conducting shepherd are.

(A) 0, 0   
(B)
(C) 0,                              
(D) None of these

• Dimensional representation of Planck's constant is the same as  
  

(A) Gravitational Constant
(B) Torque
(C) Momentum
(D) Angular Momentum

• The deflecting couple in a galvanometer is given by________
  

(A)                                 
(B) NAIB
(C)                                                     
(D) None of these

• An Inductor may store energy in its           
  

(A) Coil
(B) Electric Field
(C) Magnetic Field
(D) Both B and C

• In CRO, the time base generator circuit is connected to the:    
  

(A) X-Plate
(B) Y-Plate
(C) Electron Gun
(D) Accelerating Electrodes

• In a c Circuit at resonance, the phase difference between current and voltage is
  

(A) 90°                                         
(B) 180°
(C) 0°                                                                   
(D) 360°

• Once the resistance of material drops to zero, the    
  

(A) Energy is dissipated
(B) Current is dissipated
(C) Energy and current both are dissipated
(D) Energy and current both are not dissipated

• Radius of 3rd Bohr orbit in hydrogen atom is greater than radius of 1st orbit by
  

(A) 2                                 
(B) 3
(C) 4                                 
(D) 9

• Component in generator which consumes energy is called           
  

(A) Commutator              
(B) Split rings
(C) Capacitor                   
(D) Load

• Solid state detector is basically:
  

(A) NPN Transistor
(B) PNP Transistor
(C) PN Junction
(D) LED

• Half Life of 9138Sr is 9.70 hrs. Its decay constant is:  
  

(A) 1.99x10^-5 s   
(B) 1.99x10^-2s
(C) 1.99x 10⁵ s                           
(D) 1.99 hrs

• The circuit which changes input signal at output with phase difference of 180° is called
  

(A) Amplifier                    
(B) Inverter
(C) Non-Inverter              
(D) Switch

• Electromagnetic waves do not transport           
  

(A) Energy                        
(B) Momentum
(C) Charge                        
(D) Information

• One Tesla is  
  

(A) N A m                         
(B) N A^-1 m"1
(C) 10 NAm   
(D) None of these

PHYSICS HSSC-II
Time allowed: 2:35 Hours
Total Marks: 68

Note: Answer any fourteen parts from Section ‘B’ and any two questions from Section 'C' on the separately provided answer book. Use supplementary answer sheet i.e. Sheet-B if required. Write your answers neatly and legibily.

SECTION - B (Marks 42)

Q. 2 Attempt any FOURTEEN parts. The answer to each part should not exceed 3 to 4 lines: (14 x 3 = 42)

• Define Electric Flux and give its unit.
• What is the difference between electrical potential energy and electric potential at any point of an electric field?
• Define electric power. Obtain the maximum power equation.
• Why does the resistance of a Conductor rise with temperature?
• How can you use a magnetic field to separate isotopes of chemical element?
• Does the Induced emf in a circuit depend on the resistance of the circuit? Does the induced current depend on the resistance of the circuit?
• What is stable or dead beat Galvanometer?
• In a transformer, there is no transfer of charge from the primary to the secondary. How is, then the power transferred?
• What is a Parallel Resonance circuit? Write down its properties.
• Explain the existence of magnetic domains in Ferromagnetic material.
• Why do not we observe Compton effect with visible light?
• If the speed of light were infinite, what would the equations of special theory of Relativity reduce to?
• Why are charge carriers not present in the depletion region?
• Find the mass m of a moving object with speed 0.8 C.
• How can the spectrum of hydrogen contain so many lines, when hydrogen contains only one electron?
• What is the effect of forward biasing of a diode on the width of depletion region?
• What do we mean by the term Critical mass?
• What factors make a fusion reaction difficult to achieve?
• An A.C Voltmeter reads 250 V. What is its peak and instantaneous values if the frequency of alternating voltage is 50 Hz?

SECTION - C (Marks 26)

Note: Attempt any TWO questions.  (2 x 13 = 26)

Q.3 a. Define Mutual- Induction.    02      
b. Derive an expression for energy stored in an Inductor. Also express the energy in term of magnetic field.        06
c. A permanent magnet DC motor is run by a battery of 24 volts. The coil of the motor has a resistance of 2 ohms. It develops a back e.m.f of 22.5 volts when driving the load at normal speed. What is the current when motor just starts up? Also find the current when motor is running at normal speed?    05

Q. 4 a. What is a Transistor? Describe the construction and operation of a transistor. Also find an expression for its gain.  1+2+2+4
b. The current flowing into the base of a transistor is 100 µA . Find its collector current Ic its emitter current Ie and the ratio Ic/Ie ,if the value of current gain βis
100. 04

Q.5 a. How are X-rays produced? What are the important properties of X-rays?     5+4
b. Calculate the longest wavelength of radiation for the Paschen series.         04