Respuesta :
Answer:
Explanation:
Given the electric field
E=(2.5• j + 3.5• k) ×10³ N/C
Given the radius of the circular path r=2.5m.
Φ=?
Flux In an electric field is given as
Φ=∮E•dA. From r=0 to r=2.5m
Given that A of a striker is
The area is in yz plane then, it's normal will be in x-direction
A=πr²
Then, dA=2πrdr •i
Φ=∮E•dA. From r=0 to r=2.5m
Φ=∮(2.5j + 3.5k)×10³•(2πrdr i)From r=0 to r=2.5m
Note that, i•i=j•j=k•k=1
i•j=j•i=k•i=i•k=j•k=k•j=0
Then,
Φ=10³∮ 0dr From r=0 to r=2.5m
Φ= 0 Nm²/C
b. When it is directed in the angle of 45° between above xy
Then,
dA=(2πrCos45 i + 2πrSin45 j) dr
Φ=∮E•dA. From r=0 to r=2.5m
Φ=∮(2.5j + 3.5k)×10³•(2πrCos45dr i + 2πrSin45 j). From r=0 to r=2.5m.
Φ=10³∮(2.5j + 3.5k)•(2πrCos45dr i + 2πrSin45 j). From r=0 to r=2.5m.
Φ=10³∮ 5πrSin45 dr
Φ=10³×5π×Sin45 [r²/2] r=0 r=2.5m
Φ=10³ ×5π×Sin45×½[2.5²-0²]
Φ=10³× 5π × Sin45 × ½ × 6.25
Φ=10³×34.71
Φ=34.71×10³ Nm²/C
a. The electric flux through a circular area of radius 2.5 m that lies in the yz-plane is 0 Nm²/C
b. The electric flux when its area vector is directed at 45° above the xy-plane is 3.471 × 10⁴ Nm²/C
a.
The electric flux through a circular area of radius 2.5 m that lies in the yz-plane is 0 Nm²/C
Electric flux
The electric flux is given by Ф = ∫E.dA where
- E = electric field and
- dA = differential area vector.
Since the electric field is E = (2.5 j + 3.5 k) × 10³ N/C and the area is circular, A = πr² and dA = 2πrdr.
Since we require the flux through the yz plane, the normal to that surface is in the x - direction. So, the differential area is dA = (2πrdr)i
Electric flux through the area in the yz plane
So, Ф = ∫E.dA
Ф = ∫[(2.5 j + 3.5 k) × 10³ N/C].(2πrdr)i
Ф = ∫[(2.5 j.(2πrdr)i + 3.5 k.(2πrdr)i) × 10³ N/C]
Ф = ∫[((5πrdr)j.i + (7.0πrdr)k.i) × 10³ N/C]
Ф = ∫[((5πrdr) × 0 + (7.0πrdr) × 0) × 10³ N/C] Since j.i = k.i = 0
Ф = ∫[(0 + 0) × 10³ N/C]
Ф = ∫[0 × 10³ N/C]
Ф = ∫0 N/C]
Ф = 0 Nm²/C
So, the electric flux through a circular area of radius 2.5 m that lies in the yz-plane is 0 Nm²/C
b.
The electric flux when its area vector is directed at 45° above the xy-plane is 3.471 × 10⁴ Nm²/C
Since the area vector is directed 45° above the xy plane, the differential area vector dA = (2πrdrcos45°)i + (2πrdrsin45°)j = (2πrdr × 1/√2)i + (2πrdr × 1/√2)j = (√2πrdr)i + (√2πrdr)j
Electric flux through area directed 45° to the xy plane
So, the electric flux, Ф = ∫E.dA
Ф = ∫[(2.5 j + 3.5 k) × 10³ N/C].[(√2πrdr)i + (√2πrdr)j]
Ф = ∫[(2.5 j.(√2πrdr)i + 3.5 k.(√2πrdr)i + 2.5j.(√2πrdr)j + 3.5k.(√2πrdr)j) × 10³ N/C]
Ф = ∫[(2.5(√2πrdr)j.i + 3.5(√2πrdr)k.i + 2.5(√2πrdr)j.j + 3.5(√2πrdr)k.j) × 10³ N/C]
Ф = ∫[(2.5(√2πrdr) × 0 + 3.5(√2πrdr) × 0 + 2.5(√2πrdr) × 1 + 3.5(√2πrdr) × 0) × 10³ N/C] Since j.i = k.i = k.j = 0 and j.j = 1
Ф = ∫[(0 + 0 + 2.5(√2πrdr) + 0) × 10³ N/C]
Ф = ∫[(2.5(√2πrdr)) × 10³ N/C]
We integrate r from r = 0 to 2.5 m since r = 2.5 m.
So, Ф = ∫[(2.5(√2πrdr)) × 10³ N/C]
Ф = (2.5(√2π)∫rdr) × 10³ N/C
Ф = (2.5(√2π)[r²/2]₀²) × 10³ N/C
Ф = (2.5(√2π)[(2.5 m)² - (0 m)²]/2) × 10³ N/C
Ф = (2.5(√2π)[(6.25 m²) - (0 m²)]/2) × 10³ N/C
Ф = (2.5(√2π)[6.25 m²]/2) × 10³ N/C
Ф = (2.5(√2π)[3.125 m²]) × 10³ N/C
Ф = (7.8125√2π m²]) × 10³ N/C
Ф = (24.544√2 m²]) × 10³ N/C
Ф = 34.71 m²] × 10³ N/C
Ф = 3.471 × 10⁴ Nm²/C
The electric flux when its area vector is directed at 45° above the xy-plane is 3.471 × 10⁴ Nm²/C
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