A bird is standing on an electric transmission line carrying 3000 A of current.

Question

A bird is standing on an electric transmission line carrying 3000 A of current. A wire like this has about 3.0×105/m 3.0 10 5 m of resistance per meter. The bird’s feet are 6 cm apart. The bird, itself, has a resistance of about 4×10^5 .

Q1) What current goes through the bird? A) 1.4x10^-8 A , B) 1A C) 1.5mA , D) 2.3nA ?

Q2) What is the power dissipated by the bird? A) 17.4 mW , B) 1 W , C) 7.3X10^-11 W D) 25.4mW

Q3) By how many Joules of energy does the bird heat up every hour? A) 3.14mJ , B) 2.1mJ , C) 1J , D)2.6X10^-7 J

Explanation / Answer

1) Voltage are equal as bird and wire are in parallel

I2R2 = I1R1

I2 = I1*R1/R2 =3000*(3*10^-5*0.06)/(4*10^5) = 1.35 *10^-8 A....OPTION A

2) power = i^2 R = (1.35*10^-8)^2*4×10^5 =7.3*10^-11 W....option C

3) eNERGY = POWER *TIME = 7.3*10^-11*3600=2.63*10^-7 J....option D

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