If three resistances R1 ,R2 and R3 are connected in series . Such that R1 > R2 > R3 , then their equivalent resistance will be : -

1 ) If three resistances R1 , R2 and R3 are connected in series . Such that R1 > R2 > R3 , then their equivalent resistance will be : -

A ) Re > R1 ,                            B ) Re < R1 ,

C ) Re = R1 ,                           D ) All of these ,

Correct Answer : -  A ) Re > R1 ,

Because Re = R1 + R2 + R3 .  So Re will be greater than all resistors ( R1 , R2 and R3 ) .

 

2 ) How much heat  a 100 watt bulb will generate in 1 hour ?

A ) 0.36 MJ ,                                            B ) 0.36 kJ ,

C ) 3.6 MJ ,                                              D ) None of these ,

Correct Answer : -  A ) 0.36 MJ ,

Solution : -

Formula : -

Here we use power formula : -

P = W / t  =  E / t  ,

So ,  E = P x t .

E  =  100 x ( 3600 secs ) = 360000  =  0.36 M joule .  Answer .

 

3 )  When stream lines are close to each other , so pressure will be …… ,

A ) large ,                                         B ) small ,

C ) not effected ,                                      D ) None of these ,

Correct Answer : -  B ) small ,

If stream lines does not cross each other , then flow is steady .

 

4 )  A convex lens is dipped in a liquid , whose refractive index is equal to material of lens . Its focal length will become …………. ,

A ) infinite ,                                              B ) finite ,

C ) smaller ,                                     D ) greater ,

Correct Answer : -  A ) infinite ,    

 

5 ) The equivalence of two systems in thermal equilibrium is represented by …………….. ( temperature ) .

 

6 ) Elastic waves in solids are ………………. ,

A ) longitudinal ,                                              B ) transverse ,

C ) both of these ,                                    D ) None of these ,

Correct Answer : -  B ) transverse ,

 

7 ) The speed of waves in stretched string depends upon the ………… ( tension in the string ) .

 

8 ) ……...... is a process of releasing electron from heated metal surface .

A ) Thermionic emission ,                               B ) Photoelectric effect ,

C ) X- rays emission ,                                      D ) None of these ,

Correct Answer : -  A ) Thermionic emission ,

 

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