Question

Heater A
Power-100W
Voltage-220V
Resistance-?
Current-?

Heater B
Power-150W
Voltage-220V
Resistance-?
Current-?​

Answer 1

Solution :-

As we know that

Power = V²/R

Also V = IR

Now as given

Heater A

Power = 100W

Voltage = 220 V

As Power = V²/R

So

=> R = V²/Power

=> R = (220)² ÷ 100

=> R = 48400 ÷ 100

=> R = 484 Ω

As V = IR

So

=> V ÷ R = I

=> I = 220 ÷ 484

=> I = 0.4545454....

=> I = 0.46 Ampere

____________________________

Heater B

Power = 150W

Voltage = 220 V

As Power = V²/R

So

=> R = V²/Power

=> R = (220)² ÷ 150

=> R = 48400 ÷ 150

=> R = 322.666.......

=> R = 322.67 Ω

As V = IR

So

=> V ÷ R = I

=> I = 220 ÷ 322.67

=> I = 0.681811...

=> I = 0.682 Ampere

Answer 2

Formula To Be Used :

$Power \: = \: \frac{ {V}^{2} }{R}$

And V = IR

For Heater 1 we have :

Power-100W

Voltage-220V

$P= \frac{ {V}^{2} }{R} \\ \\ 100 = \frac{ {220}^{2} }{R} \\ \\ 100R = 48400 \\ \\ R= 484 \: ohm$

Current = V = IR

220 = I × 484

I = 220/484 = 0.46 Ampere (approximately)

For Heater 2 we have :

Power-150W

Voltage-220V

$P = \frac{ {V}^{2} }{R} \\ \\ 150 = \frac{ {220}^{2} }{R} \\ \\ 150R = 48400 = 322.67 \: ohm \: (approximately)$

Current = V = IR

220 = I × 322.67

I = 220/322.67 = 0.682 Ampere (approximately)

We know very well that according to Ohm's law ,

Volt = Current × Resistance

V = I×R

Using it we can get I (Current) ,

Current = Volt / Resistance

I = V/R

I = 220 volt / 50 ohm = 4.4 A

The required current to be drawn = 4.4 A

Who gave Ohm's law ?

=> A German physicist named George Simon Ohm studied the relationship between electric current and potential across the ends of a conductor. He did it in 1826.

He gave a law which states that the electric currentflowing in a conductor is directly proportional to the potential difference across the ends of the conductor provided the temperature and other physical conditions of the conductor remain the same.

Mathematically we can say that :

V = IR