Which has a higher resistance: a 50 W-220 V lamp or a 25 W-220 V lamp ? Calculate the ratio of the resistances.

Explanation

Under a constant (fixed) applied voltage (V), (Voltage)
`"Resistance"= (("voltage")^(2))/("Power")`
or `R= (V^(2))/(P)`
Resistance of the first bulb,
`R_(1)= (V^(2))/(50)`
Resistance of the second bulb
`R_(2)= (V^(2))/(25)`
`:. (R_(2))/(R_(1))= 2` or `R_(1)= 2R_(1)`
`R_(2) gt R_(1)`, 25W bulb has higher resistance. Resistance of 25 W lamp bulb is twice the resistance of 50 W lamp bulb.