Physics Ncert Solutions Class 12th

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New answer posted

3 months ago

0 Follower 4 Views

A
alok kumar singh

Contributor-Level 10

According to question, we can write

10 = 1 2 a t 2 . . . . . . . . . . . . . . . ( 1 ) a n d

1 0 + x = 1 2 a ( 2 t ) 2 . . . . . . . . . . . . . . . . ( 2 )

X = 1 2 A [ ( 2 t ) 2 t 2 ] = 3 ( 1 2 a t 2 ) = 3 0 m

New answer posted

3 months ago

0 Follower 2 Views

A
alok kumar singh

Contributor-Level 10

Given, λ=8mm,v=8mm,v=3*108

E=ε0sin[kxωt]j^

k=2πλ=2π8*103=π4*103

E=60sin[k(xωkt)]j^

E=60sin[π4*103[xvt]]j^[?ωk=v]

E=60sin[π4*103[x3*108t]]j^v/m

Now E0B0=C

B0 = 603*108=20108=2*107 B=2*107[π4*103[x3*108t]]k^T

New answer posted

3 months ago

0 Follower 4 Views

A
alok kumar singh

Contributor-Level 10

 P=E2R= (NAdBdt)2*4ACρl

p'= (NA2dBdt)2*4AC

p'=2P

New answer posted

3 months ago

0 Follower 3 Views

A
alok kumar singh

Contributor-Level 10

2.16 Electric field on one side of a charged body is E1 and electric field on the other side of the same body is E2. If infinite plane charged body has a uniform thickness, then electric field due to one surface of the charged body is given by,

E1? = σ2ε0n? ………….(i)

Where,

n? = unit vector normal to the surface at a point

σ = surface charge density at that point

Electric field due to the other surface of the charged body is given by

E2? = σ2ε0n? ………….(ii)

Electricfieldatanypoint due to the two surfaces,

E2?-E1?=σ2ε0n?+σ2ε0n?=σε0n? ……(iii)

Sinceinsideaclosedconductor,E1?=0,

E? = E2? = σε0n?

Therefore, the electric field just outside the conductor is σε0n?

W

...more

New answer posted

3 months ago

2.31 (a) Two large conducting spheres carrying charges Q1 and Q2 are brought close to each other. Is the magnitude of electrostatic force between them exactly given by Q1Q2 /4 πε0r2 , where r is the distance between their centres?

(b) If Coulomb's law involved 1/ r3 dependence (instead of 1/ r2 ), would Gauss's law be still true ?

(c) A small test charge is released at rest at a point in an electrostatic field configuration. Will it travel along the field line passing through that point?

(d) What is the work done by the field of a nucleus in a complete circular orbit of the electron? What if t

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A
alok kumar singh

Contributor-Level 10

2.31 The force between two conducting spheres is not exactly given by the expression Q1Q2 /4 ? ? 0r2 , because there is non-uniform charge distribution on the spheres.

Gauss's law will not be true, if Coulomb's law involved 1r3 dependence, instead of 1r2 , on r

Yes. If a small test charge is released at rest at a point in an electrostatic field configuration, then it will travel along the field lines passing through the point, only if the field lines are straight. This is because the field lines give the direction of acceleration and not the velocity.

Whenever the electron completes an orbit, either circular or elli

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New answer posted

4 months ago

0 Follower 6 Views

P
Payal Gupta

Contributor-Level 10

13.28 The equation for deuterium-tritium fusion is given as:

H + H H e + n 2 4 1 3 1 2

 It is given that

Mass of ( H ) , m 1 1 2  = 2.014102 u

Mass of ( H ) 1 3 , m 2 = 3.016049 u

Mass of ( H e ) , m 3 2 4  = 4.002603 u

Mass of ( n ) , m 4 0 1 = 1.008665 u

Q-value of the given D-T reaction is:

Q = m 1 + m 2 - m 3 - m 4 c 2

= 2.014102 + 3 . 016049 - 4.002603 - 1.008665 c 2 u

= 0.018883 c 2 u

= 17.59 MeV

Radius of the deuterium and tritium, r 2.0 f m = 2 * 10 - 15 m

Distance between the centers of the nucleus when they touch each other,

d = r +r = 4 * 10 - 15 m

Charge on the deuterium and tritium nucleus = e

Hence the repulsive potential energy between the two nuclei is given as:

V = e 2 4 π ? 0 d

Where,

? 0  = permittivity of free space

 It is given that 1 4 π ? 0  = 9 * 10 9 N m 2 C - 2

Hence, V = ( 1.6 * 10 - 19 ) 2 4 * 10 - 15 *  9 * 10 9 = 5.76 * 10 - 14  J =

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New answer posted

4 months ago

0 Follower 2 Views

P
Payal Gupta

Contributor-Level 10

13.27 In the fission of U 92 238 , β - 10  particles decay from the parent nucleus. The nuclear reaction can be written as:

U 92 238 + n C e + 58 140 0 1 R u + 10 e - 1 0 44 99

It is given that:

Mass of a U 92 238 n u c l e u s , m 1 = 238.05079 u

Mass of a C e 58 140 n u c l e u s , m 2 =139.90543 u

Mass of a R u 44 99 n u c l e u s , m 3 = 98.90594 u

Mass of a neutron n 0 1 , m 4 = 1.00865 u

 

Q value of the above equation,

Q = m ' U 92 238 + m ' ( n ) - m ' ( 0 1 C e ) - m ' ( R u ) - 10 m e 44 99 58 140 c 2

Where

m' = represents the corresponding atomic masses of the nuclei.

m ' U 92 238 = m 1 - 92 m e

m'( C e ) 58 140 = m 2 - 58 m e

m'( R u ) 44 99  = m 3 - 44 m e

m'( n ) 0 1 = m 4

Substituting these values, we get

Q = m 1 - 92 m e + m 4 - m 2 + 58 m e - m 3 + 44 m e - 10 m e c 2

= m 1 + m 4 - m 3 - m 2 c 2

= 238.05079 + 1.00865 - 98.90594 - 139.90543 c 2 u

=0.24807 c 2 u

= 231.077 MeV

New answer posted

4 months ago

0 Follower 4 Views

P
Payal Gupta

Contributor-Level 10

13.26 For the emission of C 6 14 , the nuclear reaction is:

R a P b + C 6 14 82 209 88 223

We know that:

Mass of R a 88 223 , m 1 = 223.01850 u

Mass of P b 82 209 , m 2  = 208.98107 u

Mass of C 6 14 , m 3 = 14.00324 u

Hence, the Q-value of the reaction is given as:

Q = ( m 1 - m 2  - m 3 ) c 2

= (223.01850 - 208.98107 - 14.00324) c 2 u

= 0.03419 c 2 u

= 0.03419 MeV = 31.848 MeV

Hence, the Q-value of the nuclear reaction is 31.848 MeV, since the value is positive, the reaction is energetically allowed.

For the emission of H e 2 4 , the nuclear reaction is:

R a R n + H e 2 4 86 219 88 223

We know that:

Mass of R a 88 223 , m 1 = 223.01850 u

Mass of R n 86 219 , m 2  = 219.00948 u

Mass of H e 2 4 , m 3 = 4.00260 u

Hence, the Q-value of the reaction is given as:

Q = ( m 1 - m 2 &n

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New answer posted

4 months ago

0 Follower 5 Views

P
Payal Gupta

Contributor-Level 10

13.24 If a neutron n 0 1 )  is removed from C a 20 41 , the corresponding reaction can be written as:

C a 20 41 C a 20 40 + n 0 1

The separation energies are

For C a 20 41  : Separation energy = 8.363007 MeV

For A l 13 27  : Separation energy = 13.059 MeV

It is given that

m( C a ) 20 40  = 39.962591 u

m( C a ) 20 41 = 40.962278 u

m( n 0 1 ) = 1.008665 u

 

The mass defect of the reaction is given as:

Δm = m C a ) 20 40 + (  m( n 0 1 ) - m( C a ) 20 41

= 39.962591 + 1.008665 - 40.962278

= 8.978 * 10 3 u

=8.363007 MeV

 

For A l 13 27 , the neutron removal reaction can be written as

A l 13 27 A l 13 26 + n 0 1

It is given that

m( A l ) 13 26 = 25.986895 u

m( A l ) 13 27  = 26.981541 u

m( n 0 1 ) = 1.008665 u

The mass defect of the reaction is given as:

Δm = m( A l ) 13 26 +  m( n 0 1 ) - m( A l ) 13 27

= 25.

...more

New answer posted

4 months ago

0 Follower 5 Views

P
Payal Gupta

Contributor-Level 10

13.15 The given nuclear reaction is

H11 + H13  H12 + H12

Atomic mass

m ( H11 ) = 1.007825 u

m ( H12 ) = 2.014102 u

m ( H13 ) = 3.016049 u

The Q-value of the reaction can be written as:

Q = mH11+mH13-2m(H12)c2

1.007825+3.016049-2*2.014102c2

= (-4.33 *10-3 ) c2

But 1 u = 931.5 MeV/ c2

Q = -4.0334 MeV

The negative Q-value of the reaction shows that the reaction is endothermic.

The given nuclear reaction is

C612 + C612  Ne1020 + He24

Atomic mass

m ( C612 ) = 12.000000 u

m ( Ne1020 ) = 19.992439 u

m ( He24 ) = 4.002603 u

The Q-value of this reaction is given as:

Q = 2mC612-mNe1020-m(He24)c2

2*12.0-19.992439-4.002603c2

=4.958 *10-3c2 u

=4.958 *10-3*931.5

=4.6183 MeV

...more

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