EASY
12th West Bengal Board
IMPORTANT
Earn 100

The internal resistance of a 100 V battery is 5Ω. Its emf as measured by a voltmeter connected across it shows 20% error. What is the resistance of the voltmeter?

Important Questions on Current Electricity

HARD
12th West Bengal Board
IMPORTANT
Two coils have equivalent resistance 12Ω and 53Ω respectively in series and parallel combinations. What are the resistances of the coils? 
HARD
12th West Bengal Board
IMPORTANT
A battery and a series combination of resistances 2.25 Ω and 1 Ω are connected to a parallel combination of resistance 3 Ω and 1 Ω. The internal resistance of the battery is 0.1 Ω and its emf is 2 V. Calculate the magnitude of current flowing through the resistances. 
MEDIUM
12th West Bengal Board
IMPORTANT
Show that when a battery of negligible internal resistance is connected through a galvanometer of resistance 80 Ω and 20 Ω (in series), the current that flows through the galvanometer reduces to 117th part of it when a shunt of 1 Ω resistance is connected to the galvanometer. 
EASY
12th West Bengal Board
IMPORTANT
An electric heater of 140 Ω resistance and current carrying capacity of 1.2 A is to be connected with 210 V d.c. mains. Find the minimum value of additional resistance to be introduced into the circuit. 
HARD
12th West Bengal Board
IMPORTANT
Two identical cells of emf 1.5 V are connected in series. When the combination is connected in series with a resistance and a galvanometer, the current through the circuit is 1 A. If the two cells be connected in parallel, then the current through the circuit becomes 0.6 A. Calculate the internal resistance of the cells.
MEDIUM
12th West Bengal Board
IMPORTANT
A B C is a triangle made up wire. The resistance of the sides A B, B C and C A are respectively 40,60 and 100 Ω. What is the equivalent resistance between the points A and B?
MEDIUM
12th West Bengal Board
IMPORTANT
A lump of copper of mass 10 gms and of density 9 gm/cc is given. What should be the length and cross-section of the wire made from it so that its resistance is 2 ohms. (Given specific resistance of copper is 1.8×10-6Ωcm
MEDIUM
12th West Bengal Board
IMPORTANT
When a resistance of 7 ohms is connected across the terminals of a cell, the current through the circuit is 1.1 amp. When the resistance is increased to 13 ohms, the current is 0.67 amp. Determine the emf of the cell and its internal resistance.