Question

Two bulbs marked 200 W-250 V and 100 W-250 V are joined in

series to 250V supply. Power consumed in circuit is

Answer 1

P = 66.67 W

Step-by-step explanation:

Joule Heating

It's the process by which the electric current passing through a conductor produces heat.

Also known as Joule's first law or the Joule–Lenz law, states that the power of heating generated by an electrical conductor (P) is proportional to the product of its resistance (R) and the square of the current (I).

It can be described by the equation that follows:

`P = I^2.R`

Also, we can calculate the voltage V with the formula of Ohm's law:

`V = I.R`

Combining both equations, power can be related to the voltage:

`\displaystyle P=(V^2)/(R)`

Given the power and the voltage, the resistance can be calculated by solving for R:

`\displaystyle R=(V^2)/(P)`

There are two bulbs marked P=200W V=250V and P=100 W V=250.

The first bulb has a resistance of:

`\displaystyle R_1=(250^2)/(200)`

`\displaystyle R_1=312.5\Omega`

The first bulb has a resistance of:

`\displaystyle R_2=(250^2)/(100)`

`\displaystyle R_1=625\Omega`

When connected in series, the total resistance is

`R = R_1 + R_2=312.5\Omega+625\Omega`

`R=937.5\Omega`

The total power consumed when connecting them to a V=250 V supply is:

`\displaystyle P=(250^2)/(937.5)`

P = 66.67 W