Question

an electric heater 920w, 230w. a)How much heat energy is produced in this heater in one second? b) calculate the resistance of the heating coil used in this electric heater. c) if the electric heater works at 115 v. what will be its power​

Answer 1

Correct rating of heater 920W,230V

• Power=P=920w
• Voltage=V=230V
• Resistance=R

We know

$\boxed{\sf P=\dfrac{V^2}{R}}$

$\\ \sf\longmapsto R=\dfrac{V^2}{P}$

$\\ \sf\longmapsto R=\dfrac{230^2}{920}$

$\\ \sf\longmapsto \boxed{\bf R=57.5\Omega}$

• CUREENT=I

Using ohms law

$\\ \sf\longmapsto I=\dfrac{V}{R}$

$\\ \sf\longmapsto I=\dfrac{230}{57.5}$

$\\ \sf\longmapsto I=4A$

• Time=1s

We know

$\boxed{\sf H=VIt}$

$\\ \sf\longmapsto H=230\times 4\times 1$

$\\ \boxed{\sf\longmapsto H=920J}$

Now

• V=115V

$\\ \sf\longmapsto P=VI$

$\\ \sf\longmapsto P=230\times 4$

$\\ \boxed{\sf\longmapsto P=920W}$