Question

Two bulbs are rated 60 W, 220 V and 60 W, 110 V respectively. Calculate the ratio of their
resistances

Answer 1

Given,
Voltage, `V_1` = 220 v
              `V_2` = 110 v

Power, `P_1 = P_2 = p = 60 w`

As  R= `V^2/P`

   `R_1` = `(V_1^2)/P = ((220 xx220))/60`

    `R_2` = `(V_2^2)/P = ((110xx110))/6`

On dividing `R_1` and `R_2`

`R_1/R_2 =(((220xx220))/60)/(((110xx110))/60) =4/1` 

∴ `R_1 : R_2 =4:1`