An electric power station ( 10 MW) transmits power to a distant load through long and thin cables. Which of the two modes of transmission would result in lessere power wastage : Power transmission of : (i) 20,000 V or (ii) 200 V?

An electric power station ( 10 MW) transmits power to a distant load t

1.	An electric power station ( 10 MW) transmits power to a distant load through long and thin cables. Which of the two modes of transmission would result in lessere power wastage : Power transmission of : (i) 20,000 V or (ii) 200 V?
Answer» Let R be the resistance cable. Here, `P = 10 MW = 10 xx 10^(6)W = 10^(7)W`. (i) `V_(1) = 20,000V`, Current `I_(1) = P/V_(1) = 10^(7)/(20,000) = 500 A` Rate of heat dissipated, `P_(1) = I_(1)^(2) R = (500)^(2)R = 25 xx 10^(4)R W` (ii) `V_(2) = 200 V`, Current `I_(2) = P/V_(2) = 10^(7)/200 = 5 xx 10^(4)A` Rate of heat dissipated, `P_(2) = I_(2)^(2) R = (5 xx 10^(4))^(2) R= 25 xx 10^(8) R W` Clearly `P_(1) lt P_(2)`, so there will be lesser power wastage during transmission at `20,000 V` than at `200 V`.

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An electric power station ( 10 MW) transmits power to a distant load through long and thin cables. Which of the two modes of transmission would result in lessere power wastage : Power transmission of : (i) 20,000 V or (ii) 200 V?

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