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A given resistor cannot carry currents e...

A given resistor cannot carry currents exceeding `20 A`, without exceeding its maximum power dissipaation ratings . By forced air cooling suppose that we increase the rate at which heat can be carried by a factor of `2`. Now the maximum current that the resistor can carry is

A

`10 A`

B

`20 sqrt(2) A`

C

`30 sqrt(2) A`

D

`40 A`

Text Solution

Verified by Experts

The correct Answer is:
B
Heat produced `prop I^(2)` , initial heat produced `= k (20)^(2)` , final heat produced ` = 2k (20)^(2)`. If final current is `I'` , then
`kI'^(2) = 2 xx k xx (20)^(2) or I' = 20 sqrt(2) A`
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