A flat iron that has a resistance of 10 ohms is used for about 4 hourshow much heat is produced if the current is 10 amperes?

Answer 1

This can be calculate quite simply using the following steps.

First calculate the power loss (as heat energy) from the iron using the relationship:

P= I2R, P is power in Watts,

I is current in Amps,

R is resistance in Ohms.

In this case P = 102 x 10

= 1000 W

Next convert 4 hours into the standard time unit, seconds.

4 hours = 60 seconds per minute * 60 minutes per hour * 4 hours

= 14400s

Finally calculate how much heat energy is produced during this time using the relationship:

E = Pt, P is power in Watts,

E is energy in Joules,

t is time in seconds.

In this case E = 1000 x 14400

= 14400000 J

Or more appropriately 14.4 MJ (megajoules).

Hope this helps,

Tom