Question

An electric lamp is marked 20w,220v.it is used for 10 hours daily.caculate:- its resistance and no of units consumed

Answer 1

$resistance = voltage^{2} \div power$


therefore putting the values

2420ohms

the units consumed will be,
P×t
20W= 0.02KW
therefore,

0.02×10
0.2kw/h