A copper wire of length `1 m` and radius is joined in series with an iron wire of length `2 m` and radius `3 mm` and a current is passed through the wire. The ratio of the current density in the copper and iron wires isA. `3//1`B. `1//3`C. `9//1`D. `1//9`

A copper wire of length `1 m` and radius is joined in series with an i

1.	A copper wire of length `1 m` and radius is joined in series with an iron wire of length `2 m` and radius `3 mm` and a current is passed through the wire. The ratio of the current density in the copper and iron wires isA. `3//1`B. `1//3`C. `9//1`D. `1//9`
Answer» Correct Answer - C In series circuit, current is same `J=(I)/(A) prop (1)/(r^(2))` `:.J_(1)r_(1)^(2)= J_(2)r_(2)^(2) :.(J_(1))/(J_(2))=(9)/(1)`

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