Q17 of 41 Page 461

An electric lamp is marked 26 W, 220V. It is used for 10 hours daily. Calculate

its resistance while glowing.

Given

Power (P) = 26W


Voltage (V) = 220V


We know that



⇒


⇒


⇒ R =


Hence the resistance is


More from this chapter

All 41 →
15

A wire of 3Ω resistance and 15cm in length is stretched to 45 cm length. Calculate (i) New resistance.

Assuming the wire has uniform cross section area.

 16

A wire of resistance 10Ω is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle?

 17

An electric lamp is marked 26 W, 220V. It is used for 10 hours daily. Calculate

energy consumed in kWh per day.

 18

The electric power consumed by a device may be calculated by the using either of the two expressions P = I2R or P = V2/R. The first expression indicates that it is directly proportional to R whereas the second expression indicates inverse proportionality. How can the seemingly different dependence of P on R in these expressions be explained.