Correct Answer - Option 2 : 5600 A
Formula Used:
1. Relation Between MMF and Magnetic field intensity (H):
MMF = HL .... (1)
Here "L" is the length of the gap
Also, MMF = Current × No. of Turns (NI)
2. Relation between Flux Density (B) and Magnetic field intensity (H):
B = μoμrH .... (2)
from equation (1) & (2),
MMF = NI = \(\frac{B}{μ_oμ_r}× L\)
Application:
Given,
B = 0.88 T
L = 8 mm
For air, μr = 1
From above formula,
MMF = \(\frac{0.88× 8 × 10^{-3}}{4π × 10^{-7}}=\frac{0.88× 8 × 10^{4}}{4π }=\frac{88× 8 × 10^{2}}{4π }\) [0.88 × 104 = 88 × 102]
Using value of π = 22/7
Hence,
MMF = \(\frac{88\times 8 \times 100}{4\times 22/7}=5600\ A\)