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In the circuit shown in fig. 7.24 , all ...

In the circuit shown in fig. `7.24` , all the resistors are rated at a maximum power of `1.00 W`. What is the maximum `emf epsilon` that the battery can have without burning up any of the resistors?

Text Solution

Verified by Experts

The correct Answer is:
`20 V`
First recognise if the `40 Omega` resistor is safe , all the other resistors are also safe.
`I^(2) R = P or I^(2) ( 40 Omega) = 1 W or I = 0.158 A`
Now, use series // parallel reduction to simplify the circuit . The upper parallel branch is `6.38 Omega . ohm's` law gives
`epsilon = ( 126.38 Omega) (0.158 A) = 20 V`
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