October 27, 2012

CHAPTER # 13 CURRENT ELECTRICITY


  If the length and diameter of conductor is double, the
      resistance is

      a) Remain same                  b) Double                    
      c) Half                                d) Four time


    The reciprocal of resistivity is called

a)     Resistance             
b)    Conduction            
c)     Conductivity           
d)    None

 One coulomb per second is equal to

a)     Joule                     
b)    Volt                       
c)     Ampere      
d)    Walt

  In the metallic conductor the current is due to flow of charge

a)     Positive                 
b)    Negative                
c)     Proton       
d)    None

 Conventional current flow from

a)     Positive to negative
b)    Negative to positive           
c)     Negative to negative  
d)    None

 The main source for the current are

a)     Two           
b)    Three   
c)     Four          
d)    Five
 The drift velocity of electron at 0oC is

a)     zero           
b)    Maximum               
c)     1 cm/sec                
d)    10 cm/sec

 In the thermocouple the heat energy is converted
    into

a)     Mechanical energy  
b)    Electric energy       
c)     Magnetic energy     
d)    None

 An electric heater 220V, 440W has a resistance

a)     2 Ω            
b)    110 Ω        
c)     0.5 Ω         
d)    20 Ω

 The heating effect of current utilized in

a)     Iron            
b)    Tube light               
c)     Fan                        
d)    Motor

 Mathematical form of ohm’s law is

a)     I = VR        
b)    I = V/R       
c)     I = R/V       
d)    R = IV

 Ohm’s law is valid for only current flowing in

a)     Conductors
b)    Transistors             
c)     Diodes      
d)    Electric Areas

 Through an electrolyte electric current is passed due to drift of

a.     Free electrons 
b.    Positive and negative ions 
c.     Free electrons and holes 
d.    Protons

 The e.m.f. of two cells can be compared by

a.     AVO meter 
b.    Voltmeter               
c.     Potentiometer        
d.    Galvanometer

The post office box is based on the principle of

a.     Galvanometer         
b.    Wheat-stone bridge
c.     Voltmeter   
d.    None



 At null point the current through the galvanometer
       is

a)     Zero          
b)    Maximum   
c)     Minimum                
d)    None

 A current of 10A flows in a conductors of 10 Ω
      resistance for 1 mint the heat produce will be

a)     102 J          
b)    6 x 102 J                 
c)     6 x 103 J                 
d)    6 x 104 J

 The unit of conductivity is

a.     Ω. M                      
b.    (η.m)-1                    
c.     Ω.m-1                                           
d.    None

 When the bulb is turned on, ohm’s law is
      applicable

a)     Yes           
b)    No                         
c)     May or may not      
d)    None

 In series circuit the net resistance is

a.     Increase     
b.    Decrease               
c.     Remain constant    
d.    None

 Joule law can be expressed as

a)     I2 Rt           
b)    IR2t      
c)     IRt2                         
d)    V2/R

 The graph b/w V and I in case of ohm law is

a)     Parabolic   
b)    Curve   
c)     Slope  
d)    Straight line


 Resistance of supper conductor is

a)     Finite         
b)    Infinite 
c)     Zero    
d)    Changes with material

 The e.m.f. of a cell or battery is the voltage b/w its
        terminals, when

a.     It is closed circuit   
b.    It is open circuit      
c.     Its internal resistance is zero 
d.    None

 The S.I unit of e.m.f. is same as

a.     Work                      
b.    Energy                   
c.     Power                    
d.    Voltage

 The main type of resistors are

a.     Two                       
b.    Three                     
c.     Four                                  
d.    Five

 In the carbon resistor their value can be find by
       their

a.     Wires                     
b.    Terminals               
c.     Color                     
d.    Spots

 The third band is written in the form of power of

a.     2               
b.    6                           
c.     8                           
d.    10

 Tolerance color means

a.     Greater      
b.    Less                                  
c.     Greater-less           
d.    None

 If the first color red and 2nd band is green and
       third band is orange, then value of resistance is

a.     20000                    
b.    24000                    
c.     25000                    
d.    None

 If the tolerance color is gold then it value is

a.     ± 2%                      
b.    ± 4%                      
c.     ± 5%                      
d.    ± 6%


 A variable resistors is called

a.     Resistance 
b.    Rheostat                
c.     Amplifier                
d.    None

 A heat sensitive resistor is called

a.     Amplifier    
b.    Diode                    
c.     Thermistor 
d.    Conductor

 The temperature co-efficient of thermistor is

a.     Positive     
b.    Negative                
c.     Zero                      
d.    None

 Thermistor can be used for the accurate
       measurement of

a.     Voltage      
b.    Resistance             
c.     Temperature           
d.    Heat

 A circuit which has only one voltage source is
       called

a.     Network     
b.    Simple circuit         
c.     Complex circuit      
d.    None

 The circuit who has more than one voltage source
       is called

a.     Network     
b.    Simple circuit         
c.     Complex circuit      
d.    None

 The algebraic sum of all the current at junction is
       zero, is Kirchoff’s  

a.     1st law                    
b.    2nd law                    
c.     3rd law                    
d.    4th law

 The algebraic sum of voltages changes around a
       closed circuit or loop is zero, is Kirchoff’s

a.     1st law                    
b.    2nd law                    
c.     3rd law                    
d.    4th law

 If the resistance of a certain length wire, diameter
      5mm is 10Ω if the diameter is charge to 10mm,
      then new resistance is               

a.     40              
b.    5                           
c.     20                          
d.    2.5

 The unit for the consumption of electrical energy
       commonly used is

a.     Joule                     
b.    Watt sec                
c.     K. watt. hr              
d.    Watt. hr

 Heat generated by 40 watt bulb is one hour is

a.     24000 J      
b.    48000 J                  
c.     144000 J                
d.    14400 J

 The principle of potentiometer

a.     P.d  length                     
b.    P.d  resistance   
c.     P.d.  area           
d.    None

A fuse is placed in series with circuit to protect
       against

a.     High power                        
b.    High voltage          
c.     High current           
d.    Over heating

 If the resistor is traversed apposite to the direction
       of current, then potential is

a.     Positive     
b.    Negative    
c.     Zero          
d.    None

 When electricity passes through the liquid then
       process is called

a.     Electro late
b.    Electrolysis            
c.     Electro-conductor               
d.    None

 Which one gives pure nature of the material

a.     Resistively 
b.    Conductivity           
c.     Temperature co-efficient     
d.    None

 Kirchoff’s 1st law is also called law of conservation of

a.     Charge       
b.    Mass                     
c.     Energy                               
d.    None

        The resistivity of a material is . If the area of cross-section of material is doubled and length is halved then the resistivity of material is:

            a)                                   b) 4
            c) 2                                  d)  / 4

     Four bulbs of 10W, 20W, 30W and 40W are connected in parallel, the bulb that will shine more is

            a) 10W                                b) 20W
            c) 30W                                d) 40W

       A source of 200V provides a current of 10.0 Amperes to a house. The power delivered by the source is

            a) 20 watt                b) 40 watt
            c) 2000 watt                        d) 200 watt

        When the battery is connected at its ends, an electric field is set up at

            a) Its ends               b) Every point  
            c) Middle                d) All of them


      The value of resistance depends upon

            a) Nature                 b) Dimension
            c) Physical state      d) All of them

      Conductance is a quantity used to describe the

            a) Physical state of the conductor
            b) Electrical properties of material
            c) Dimension of the conductor
            d) All of them

        The resistivity  of  Aluminium in Ωm is

            a) 2.59 × 10-8                       b) 2.60 × 10-8
            c) 2.63 × 10-8                       d) None of these

       The resistivity of Germanium in Ωm is

            a) 0.7 × 10-8             b) 0.5 × 10-8
            c) 0.59 × 10-8                       d) None of these

        The colour code for the colour Grey is

            a) 7                         b) 8
            c) 9                         d) 5

        A zero ohm resistor is indicated by

            a) A single silver colour band
            b) A single black band
            c) A silver black band
            d) None of these

      Thermo couples convert heat energy into

            a) Mechanical energy           b) Chemical energy
            c) Electrical energy d) None of these

      An accurate measurement of emf of a cell is made by

            a) A voltmeter                     b) An ammeter
            c) A potentiometer   d) All of them


  Do bends in a wire affect its electrical resistance

      a) Yes                           b) No
      c) Affects a little                        d) None of these

       A 50 volt battery is connected across a 10 ohm resistor. The current is 4.5A. The internal resistance of the battery is:

            a) 1.1 Ω                              b) 1.2 Ω
            c) 1.3 Ω                              d) 1.4 Ω

       A 25 watt and 40 watts bulbs were connected  an a series to a 220V line. Which electric bulb will grow more brightly?

            a) 25 watts bulb                   b) Neither will give light
            c) Both will have same incandescence
              d) none

    

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