Question

A heater is rated as 220v,880w.What is the current drawn by the heater when connected to 220v a.c. mains.Calculate the resistance of heater

Answer 1

Given:-

• Potential Difference ,V = 220 v

• Power of heater ,P = 880W

To Find:-

• Current ,I

• Resistance ,R

Solution:-

Firstly we calculate the current drawn by heater when connected to 220 v.

• P = VI

Where,

P is the Power of Heater

V is the Potential Difference

I is the Current.

Substitute the value we get

→ 880 = 220 × I

→ I = 880/220

→ I = 88/22

→ I = 4 A

Therefore, the current drawn by the heater when connected to 220 volts is 4 Ampere.

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Now we have to calculate the Resistance of the heater .

You can also use Ohm's Law to calculate the Resistance .

• P = V²/R

Where,

P is the Power

V is the Potential Difference

R is the Resistance

Substitute the value we get

→ 880 = 220²/R

→ 880 = 48400/R

→ 880×R = 48400

→ R = 48400/880

→ R = 55Ω

Therefore, the Resistance of the heater is 55 ohms.

Answer 2

Answer

• Current Drawn by heater is 4A
• Resistance of the heater is 55Ω

Explanation

Given

• Potential Difference = 220 V
• Power = 880 W

To Find

• Current drawn by the heater
• Resistance of the heater

Solution

• This question is purely based on the formulas related to power, they are,

1. P = VI
2. P = I²R
3. P = V²/R

✭ Current drawn by the heater

→ P = VI

• Power = 880 W
• Voltage = 220 V
• Current = ?

→ 880 = 220 × I

→ 880/220 = I

→ Current = 4A

✭ Resistance Offered by the heater

→ P = I²R

→ 880 = 4² × R

→ 880 = 16 × R

→ 880/16 = R

→ Resistance = 55 Ω

Other Method for Resistance!

→ P = V²/R

→ 880 = 220²/R

→ 880 = 48400/R

→ R = 48400/880

→ Resistance = 55Ω