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Magnetic flux passing through a coil is ...

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

A

0.3

B

0.4

C

0.5

D

0.6

Text Solution

Verified by Experts

The correct Answer is:
C
Emf induced is given by, `e=|-(dphi)/(dt)|implies(dphi)/(dt)`
`implies 0.72xx10^(-3)=(4xx10^(-4)-4xx10^(-5))/(t)`
`implies t=(4xx10^(-5)xx9)/(72xx10^(-5))=(1)/(2)=0.5s`
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Knowledge Check

  • Magnetic flux passing thorugh a coil is initially 4 xx 10^(-4) Wb . It reduce to 10\% of its original value in t second. If the emf induced is 0.72 mV then t in second is

    A
    `0.3`
    B
    `0.4`
    C
    `0.5`
    D
    `0.6`

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    0.25 s
    B
    0.5 s
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    D
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