12 physics electrostatics test 01 answer 5x7f

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  • 8/17/2019 12 Physics Electrostatics Test 01 Answer 5x7f

    1/4

     

    Material downloaded from http://myCBSEguide.com and http://onlineteachers.co.in 

    Portal for CBSE Notes, Test Papers, Sample Papers, Tips and Tricks

    01. = between the charges in vaccuum

    force between two charges in medium

    FV force

    FM =  

    FV Fm

    k ⇒   =  

    ⇒ , .

    02. ⇒  

    ⇒   . .

    03. = = /

    ,

    .

    04.

    .

    05. =

    ∴  F qE 

    am m

    = =   1

    2  2 = 2

    ∴   = ⇒2 = 2

    21 1 mv = (2 as) = mas ----- 2

    2 2KE m=  

    1 . 2

    m x SqE 

    KE m

    KE qES  

    = ×

    =

     

    2 E 

     

    1 E 

  • 8/17/2019 12 Physics Electrostatics Test 01 Answer 5x7f

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    Material downloaded from http://myCBSEguide.com and http://onlineteachers.co.in 

    Portal for CBSE Notes, Test Papers, Sample Papers, Tips and Tricks

    06.

    (+)

    .

    .

    + = +. + 91

     E 

    2 2

    2 2

    2 2

    ( ) ( 9 ) E = E

    (10 )

    Substituting in eq. 1

    ( ) ( 9 )

    (10 )

    (10 ) = 9x 10 = 3x

    1010a = 4x x = 9

    4

    a from change (+q)

    Or

    10 a - x = 10a - 2.5a = 7.5a from

    = 2.5

    K q K q A B

     x a x

    K q K q

     x a x

    a x a x

     x

    + +⇒   =

    + +=

    − −

    change (+9q)

     

    07.

    .

    (2 )P q l=

      .. ()

    ( θ   )

    ( ) E    ,

    .

    τ   = ⊥

    () =

    sin AB sin = 2 sin BN 

     And BN  AB

    θ θ θ  =   ⇒   =   ℓ  

    (τ   ) = 2 ℓ θ   

    (τ   ) = θ    ( = q(2 ))P l

    ∵  

    P E τ    = ×

     

    A B

    10a

    x 10a-x+qv

    +q +9qP

    B A E 

      E 

  • 8/17/2019 12 Physics Electrostatics Test 01 Answer 5x7f

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    Material downloaded from http://myCBSEguide.com and http://onlineteachers.co.in 

    Portal for CBSE Notes, Test Papers, Sample Papers, Tips and Tricks

    08. (1) lim

    q o→ 

    .

    (2) ()

    = 2 10 7 + (2 10 7)

    = . P

     

    () 2P q l= ×

     

    = 2 107  20 102 

    = 4 108 

    .

    09. ()

    ()

    2 2

    2 2

    ( )

    ( )

     

    Kq E q

    r aKq

     E qr a

    Since E q E q

    + =+

    − =+

    + = −

     

    ∴ Enet 

     

    .

    (-2x10-7

    Z

    Z

    Y

    X

    (0,0,10)cm

    2l=10+10=20cm

    (2x10-7

    )

    (0,0,-10)cm

     

    P

    E+q

    2 2r a+

    2 2r a+

    2

    E

      (+qo) E= ?

      -q

    r

    A B(-q) (+q)a o a

     θ    θ  

     θ     P

      E 

     net 

  • 8/17/2019 12 Physics Electrostatics Test 01 Answer 5x7f

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    Material downloaded from http://myCBSEguide.com and http://onlineteachers.co.in 

    Portal for CBSE Notes, Test Papers, Sample Papers, Tips and Tricks

    2 2

    -q

    2 2

    2

    2 2 2 2

    2 2

    2 2

    2 2 2 2

    2 E cos2

    2 2 cos 2

    2 (1 cos 2 )

    2 2cos 4 cos

    2 cos cos =

    2

    2

    2

    (

    q q q

    q q

    q

    q q

     Enet E E E 

     Enet E E 

     Enet E 

     Enet E E 

    a Enet E 

    r a

    a Enet E 

    r a

    kq a Enet 

    r a   r a

    k aq Enet 

    θ  

    θ  

    θ  

    θ θ  

    θ θ  

    − +

    +

    = + + +

    = + +

    = + +

    = + = +

    = +

    +

    = +

    +

    =+   +

    =

    2 2 3/2 2 2 3/2

    3

    For r >>> a (a can be neglected)

    Enet =

    ) ( )

     

    K P

    a r a

    KP

    =+ +