Heating effect of Electric Current

Electricity and Magnetism Level 1

The maximum power rating of a 20Ω resistor is 2kW . A DC sourceof negligible internal resistance and emf V volts is connected across the resistor . What is the maximum value of V so that the heat produced does not melt the resistor?

V = 220 volts V = 120 volts V = 240 volts V = 200 volts

Ankit Vijay by Ankit Vijay , 22, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Ankit Vijay
May 29, 2014

L e t V m b e t h e m a x i m u m v a l u e , t h e n h e a t p r o d u c e d p e r s e c o n d i s H t = V m 2 R T h u s , f o r H t = 2 k W , w e m u s t h a v e V m 2 = 2 × 10 3 × 20 = 4 × 10 4 S o V m = 200 V o l t s Let\quad { V }_{ m }\quad be\quad the\quad maximum\quad value,\quad then\quad heat\quad produced\quad per\quad second\quad is\\ \quad \quad \quad \quad \quad \quad \quad \\ \frac { H }{ t } =\frac { { { V }_{ m }^{ 2 } } }{ R } \\ Thus,\quad for\frac { H }{ t } =2kW,\quad we\quad must\quad have\\ { V }_{ m }^{ 2 }=2\times { 10 }^{ 3 }\times 20=4\times { 10 }^{ 4 }\\ So\quad { V }_{ m }=200Volts

3 Helpful 0 Interesting 0 Brilliant 0 Confused

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...