Magnetic flux passing through a coil is initially 4 × 10- 4 Wb. It reduces to 10 % of its original value in ‘t’ second. If the e.m.f. induced is 0.72 mV then ‘t’ in second is

Question

Magnetic flux passing through a coil is initially 4 × 10- 4 Wb. It reduces to 10 % of its original value in ‘t’ second. If the e.m.f. induced is 0.72 mV then ‘t’ in second is (A) 0.3 (B) 0.4 (C) 0.5 (D) 0.6

Tardigrade Admin · Accepted Answer

Magnetic flux gets reduced to 10 % of its original value in time t. Change in magnetic flux |Δ φ|=0.9 φ text initial ∴ |Δ φ|=0.9 × 4 × 10-4=0.36 × 10-3 Wb Emf induced in the coil E =0.72 × 10-3 V Using E =(|Δ φ|/ t ) ∴ 0.72 × 10-3=(0.36 × 10-3/ t ) ⇒ t =0.5 s

Q. Magnetic flux passing through a coil is initially $4 \times 1 0^{- 4} Wb$ . It reduces to $10%$ of its original value in ‘ $t$ ’ second. If the e.m.f. induced is $0.72 mV$ then ‘ $t$ ’ in second is

$0.3$

$0.4$

$0.5$

$0.6$

Q. Magnetic flux passing through a coil is initially 4×10−4Wb. It reduces to 10% of its original value in ‘t’ second. If the e.m.f. induced is 0.72mV then ‘t’ in second is

0.3

0.4

0.5

0.6

Magnetic flux gets reduced to 10% of its original value in time t. Change in magnetic flux ∣Δϕ∣=0.9ϕinitial ​ ∴∣Δϕ∣=0.9×4×10−4=0.36×10−3Wb Emf induced in the coil E=0.72×10−3V Using E=t∣Δϕ∣​ ∴0.72×10−3=t0.36×10−3​ ⇒t=0.5s

Q. Magnetic flux passing through a coil is initially $4 \times 1 0^{- 4} Wb$ . It reduces to $10%$ of its original value in ‘ $t$ ’ second. If the e.m.f. induced is $0.72 mV$ then ‘ $t$ ’ in second is

$0.3$

$0.4$

$0.5$

$0.6$