1 ) The de Broglie wavelength of electron moving with velocity of 1.5 x 10 ^ 8 m / s is equals to that of photon . The ration of K.E if electron to that of photon is : -

1 )  The de Broglie wavelength of electron moving with velocity of 1.5 x 10 ^ 8  m / s   is equals to that of photon . The ration of K.E if electron to that of photon is : -

A ) 4 ,                                           B ) 8 ,

C ) 12 ,                                         D ) None of these ,

Correct Answer : -  A ) 4 ,

Solution : -

2 ) A projectile have Same range R for two angles of projection and t1 , t2 at time of flight in the two cases , then what is product of two times of flight ?

A ) 2R / g ,                                               B ) 4R / g ,

C ) 8R / g ,                                               D ) None of these ,

Correct Answer : -  A ) 2R / g ,

Solution : -

 

3 ) If t1 and t2 are the times of flight of two particles having the same initial velocity  ' vi '  and range R on the horizontal .  So  ( t1 ) ²  +  ( t2 ) ²  ?

A )  2 vi² / g ,                                            B ) 4 vi² / g ,    

C )  8 vi² / g ,                                           D ) None of these ,

Correct Answer : - B ) 4 vi² / g ,

Solution : -

 

4 )  When current in a coil changes to 12 ampere from 3 ampere in 9 x 10 ^ ( -3 ) sec , then emf induced in the coil is 4 volts . The self inductance of coil is ?

A ) 4 x 10 ^ ( +3 )  Henry  ,              B ) 4 x 10 ^ ( -3 )  Henry  ,

C ) 10 ^ ( -6 )  Henry  ,                     D ) 10 ^ ( -9 )  Henry  ,

Correct Answer : -    B ) 4 x 10 ^ ( -3 )  Henry  ,

Solution : -

Formula : -

We have formula  that : -

E = d ( NΦ ) / dt  , 

E = d ( LI ) / dt  ,  

E  =   L . dI / dt  ,

E   =   L . dI /dt  , 

4  =  ( L x 9 ) / 9 x 10 ^ ( -3 )    ,

L = 4 x 10 ^ ( -3 )    Henry  ,   Answer .