Question

An electric heater of resistance 8 ohm draws 15 A from the service mains in 2 hours calculate the rate at which heat is developed in the heater.​

Answer 1

Given

• Resistance of heater (R)=8ohm
• Current (I) = 15A
• Time (t) = 2hours

Find out

• Heat developed in the heater

Solution

★The rate at which heat is developed and in the heater is equivalent to power.

➠ P = I²R

➠ P = (15)² × 8

➠ P = 225 × 8

➠ P = 1800 J/s

Therefore, heat is produced by the heater at the rate of 1800 J/s.

Additional Information

• P = VI
• P = V²/R
• P = W/t
• 1 watt =joule/second =volt/ampere

$\rule{200}3$

Answer 2

Given :

An electric heater of resistance 8 ohm draws 15 A from the service mains in 2 hours.

To Find :

Calculate the rate at which heat is developed in the heater.

Solution :

• Resistance (R) = 8ohm
• Current (I) = 15 A
• Time (t) = 2hours

As we know that

➪ P = I²R

➪ P = (15)² × 8

➪ P = 15 × 15 × 8

➪ P = 1800 J/s

Hence, heat developed by a heater is 1800 J/s

Note : -

★ Heat developed in heater = Power