Question

Calculate the heat devolped in 30minutes when 3A current flows through an electric iron boxdesigned to work under 230V

Answer 1

Current,I = 3A

potential difference,V= 230 V

time, t= 30 minute ( convert minute into second)

30 × 60= 1800 sec

we have to find Resistance

By Ohm's law

R = V÷ I

= 230 ÷ 3

R= 76.66 ohm ( by round off)

R= 77 ohm

Now, Heat= I²×R×T

= (3)² × 77 × 1800

= 1247400

Heat= 1.2475 × 10⁶ joules