Question

A nichrome wire used as a heater coil has a resistance of 2ohm/m. for a heater of 1kw at 200v,the length required is?

Answer 1

we know, power = V²/R
Here , V is the potential difference
And R is the resistance of wire.

Given,
Resistance of wire per unit length = 2 Ω/m
Let length of wire is L
Then, resistance of wire = resistance of wire per unit length × length of wire
= 2L Ω
Power = 1kW = 1000 watt
Potential difference , V = 200V

∴ 1000 = (200)²/2L
1000 = 40000/2L
L = 20 m

Hence, length of wire is 20m

Answer 2

Answer:

we know, power = V²/R Here ,

V is the potential difference And R is the resistance of wire.

Given,

Resistance of wire per unit length = 2 Ω/m Let length of wire is L

Then,

resistance of wire = resistance of wire per unit length × length of wire

= 2L Ω Power = 1kW = 1000 watt

Potential difference ,

V = 200V∴ 1000 = (200)²/2L1000 = 40000/2LL = 20 m

Hence, length of wire is 20m