Question Details

Let E ( x , y , z ) = 2 x 2 i ^ + 5 y j ^ + 3 z k ^ the value of ∭v ( . E ) d V , where v is the volume enclosed by the unit cube defined by 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and 0 ≤ z ≤ 1 is

Options

A

3

B

8

C

10

D

5

Correct Answer :

10

Solution :

The correct option is 10.

To find the value of the volume integral V(E)dV over the unit cube V, we first need to compute the divergence of the electric field vector E(x,y,z).

The given vector field is:
E=2x2i^+5yj^+3zk^

The divergence of a vector field E=Exi^+Eyj^+Ezk^ is defined as:
E=Exx+Eyy+Ezz

Substituting the components of our vector field, we obtain:
Ex=2x2Exx=x(2x2)=4x
Ey=5yEyy=y(5y)=5
Ez=3zEzz=z(3z)=3

Summing these partial derivatives gives the divergence:
E=4x+5+3=4x+8

Now, we integrate this divergence over the volume V of the unit cube defined by the boundaries 0x1, 0y1, and 0z1:
V(E)dV=010101(4x+8)dzdydx

Since the integrand depends only on x, we can separate the integrals for y and z:
V(E)dV=[01(4x+8)dx][01dy][01dz]

Evaluating the integrals for y and z:
01dy=[y]01=1
01dz=[z]01=1

Now we evaluate the integral with respect to x:
01(4x+8)dx=[2x2+8x]01=(2(1)2+8(1))-(0)=2+8=10

Multiplying these results together, we get:
V(E)dV=1011=10

Thus, the value of the triple integral is 10.

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