What is the value of resistance ot coil having impedance of 50ohm connected across 240v at 0.8 p.f?

To find the resistance of a coil with an impedance of 50 ohms connected across 240V at a power factor of 0.8, we can use the formula for power factor: ( \text{p.f.} = \frac{R}{Z} ), where ( R ) is the resistance and ( Z ) is the impedance. Rearranging gives ( R = \text{p.f.} \times Z ). Thus, ( R = 0.8 \times 50 , \text{ohms} = 40 , \text{ohms} ). Therefore, the resistance of the coil is 40 ohms.