Current Electricity and Electrical InstrumentHard

Question

A bulb is connected to an ideal battery of emf 10 V so that the resulting current is 10 mA. When the bulb is connected to 220 V mains (ideal), the current is 50 mA. Choose the correct alternative (s)

Options

A.In the first case, the resistance of the bulb is 1kΩ and in second case, it is 4.4 kΩ.
B.It is not possible since ohm’s law is not followed   
C.The increase in resistance is due to heating of the filament of the bulb when it is connected to 220 V mains
D.None of these

Solution

(i) Rbulb = = 1. kΩ
(ii) Rbulb = = 4.4 kΩ
since increase in temperature increases resistance when it is connected to 220 V mains. 

Create a free account to view solution

View Solution Free
Topic: Current Electricity and Electrical Instrument·Practice all Current Electricity and Electrical Instrument questions

More Current Electricity and Electrical Instrument Questions

The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and ...Two weirs each of radius cross section r but of different materials are connected to gather end to end (in series). If t...Find potential of J with : - respect to G -...The voltage of clouds is 4 × 106 volt with respect to round. In a lighting strike lasting 100msec, a charge of 4 co...A continuous beam of electrons emitted by a heating filament are accelerated in free space by an electric field as shown...