Two identical conducting spheres A and B carry identical charges . They are separated by a distance much longer then their diameters . Third identical conducting sphere C is uncharged , first touch to A and then B and then removed , then the force between A and B will ?

 1 )  Two identical conducting spheres A and B carry identical charges .  They are separated by a distance much longer then their diameters . Third identical conducting sphere C is uncharged , first touch to A and then B and then removed  , then the force between A and B will ?

A )  1/8 times ,                         B ) 3/8 times , 

C )  7/8 times ,                 D ) no change ,       

Correct Answer : -  B )  3/8 times ,       

Solution : -                                 

 

2 ) if two bodies of different masses initially at rest , acted upon by same force and same time , then bodies will have same …………. ,

A ) acceleration ,                                             B ) momentum ,

C ) torque ,                                              D ) None of these ,

Correct Answer : -   B ) momentum ,

Because  ∆P = F x t .

 

3 )  Compton wave shift = (h/mv)(1-cosθ)

 

4 ) An electron is placed in a box about size of an atom that is about  1 x 10^(-10) m  . What is velocity of electron ?

A ) 7.29 x 10^6  ,                             B ) 7.29 x 10^8 ,

C ) 7.29 x 10^11  ,                                   D ) None of these ,

Correct Answer : - A ) 7.29 x 10^6  , 

Solution : -

Size of an electron = ∆x  = 1 x 10^(-10) m  .

Velocity of an electron = ∆v = ?

Formula : -

As we know the mass of electron = 9.11 x 10^(-31) kg .

Planks constant = 6.63 x 10^(-34)  Js .

So , using uncertainty principle : -

Ø   ∆P . ∆x  =  h  ,

Ø   ( m . ∆v ) . ∆x  =  h  ,

Ø   ∆v = h / (m.∆x)  ,

Ø    ∆v =  {6.63 x 10^(-34)} / {9.11 x 10^(-31) x 1 x 10^(-10)}  ,

Ø    ∆v =  7.29 x 10^6    m/s   Answer .

 

5 ) In pure capacitive circuit , current is ………… the voltage .

A ) lagging ,                                             B ) leading ,

C ) None of these ,

Correct Answer : -  B ) leading ,

Voltage lags current  by  90 degree .

Now go to online quiz section and Physics Quiz 6 is uploaded related to these mcqs  , so check your preparation by this link : -

UG Online quizzes