Magnetic flux passing through a coil is initially 4 × 10 - 4 W b . It reduces to 10 % of its original value in t second. If the emf induced is 0.72 mV then t in second is

ϕ 1 = 4 × 10 - 4 Wb ϕ 2 = 0 .1 × ϕ 1 = 4 × 10 - 5 Wb ε = 0.72 m V ∴ t = ? Using ε = - d ϕ d t ⇒ d t ⇒ d ϕ ε = 4 × 10 - 4 - 4 × 10 - 5 72 × 10 - 5 = 4 × 10 - 5 ( 9 ) 72 × 10 − 5 = 1 2 = 0.5 s

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Physics - EMI/AC Question with Solution | TestHub

PhysicsEMI/ACFaraday law/Lenz lawEasy2 minPYQ_2020

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Magnetic flux passing through a coil is initially $4 \times 10^{- 4} W b$ . It reduces to $10 %$ of its original value in $t$ second. If the emf induced is 0.72 mV then $t$ in second is

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Solution:

$ϕ_{1} = 4 \times 10^{- 4} Wb$

$ϕ_{2} = 0 .1 \times ϕ_{1} = 4 \times 10^{- 5} Wb$
$ε = 0.72 m V$
$∴ t = ?$
Using $ε = - \frac{d ϕ}{d t} \Rightarrow d t \Rightarrow \frac{d ϕ}{ε}$
$= \frac{4 \times 10^{- 4} - 4 \times 10^{- 5}}{72 \times 10^{- 5}} = \frac{4 \times 10^{- 5} (9)}{72 \times 10^{- 5}} = \frac{1}{2} = 0.5 s$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:EMI/ACSubtopic:Faraday law/Lenz law

⏱ 2mℹ️ Source: PYQ_2020

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