Heating effect of Electric Current

Electricity and Magnetism Level 1

A wire of resistance 25Ω is made of manganin alloy and is connected across a car battery of 12V emf and negligible internal resistance. How much heat energy is produced in 30 minutes (in Joules) ?

H = 9.78 x 10^3 H = 10.37 x 10^3 H = 8.89 x 10^3 H = 11.39 x 10^3

Ankit Vijay by Ankit Vijay , 22, India

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2 solutions

Ankit Vijay
May 29, 2014

H e a t p r o d u c e d H = I 2 R t = V 2 R ⋅ t H = ( 12 ) 2 25 × 30 × 60 H = 10.37 × 10 3 J Heat\quad produced\\ H\quad =\quad { I }^{ 2 }Rt\quad =\quad \frac { { V }^{ 2 } }{ R } \cdot t\\ \quad \quad \quad \quad \quad \quad \quad \quad H\quad =\quad \frac { { (12) }^{ 2 } }{ 25 } \times 30\times 60\\ \quad \quad \quad \quad \quad \quad \quad \quad H\quad =\quad 10.37\times { 10 }^{ 3 }J

4 Helpful 1 Interesting 0 Brilliant 0 Confused

hey it is 30 minutes...so time will be equal to 30/60...not 30 x 60...????

A Former Brilliant Member - 7 years ago

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nope its 30*60. SI unit for time is Seconds so you'll be converting minutes into seconds by multiplying it with 60

Vignaraj Pai - 1 year, 7 months ago

Is 30 *60 correct?

Deepak Gowda - 7 years ago

joule is related to second. so we require to change min into sec. so 30*60 is correct.

Lalita Verma - 6 years, 11 months ago

Yo,

as by ohms law, V=IR, given that V = 12V , R = 25 ohms, I = V /R is substituted into P = IV

P = V^2 / R = W / t = rate of energy used,

W(energy used ) = ( V^2 . t ) / R = *12)^2 . 30 x 60 / 25 = 10.37 x 10^3 J....

Thanks.....

1 Helpful 1 Interesting 1 Brilliant 0 Confused

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