12.2 Problems
541
12.10 A network of infinite resistors is shown in Fig. 12.10. Find the effective resistance of the network between terminal points A and B.
Fig. 12.10
12.11 What equal length of an iron wire and a constantan wire, each 1 mm diameter,
must be joined in parallel to give an equivalent resistance of 2 ? (resistivity
of iron and constantan are 10 and 49 μ cm, respectively).
[University of London]
12.12 A coil of wire has a resistance of 20 at 25 ◦ C and 25.7 at 100 ◦ C. Calculate the temperature coefficient.
[University of London]
12.13 A wire of resistance 0.1 /cm is bent to form a square ABCD of side 10 cm.
A similar wire is connected between the corners B and D to form the diagonal BD. Find the effective resistance of this combination between A and
C. A battery of negligible internal resistance is connected across A and C.
Calculate the total power dissipated.
[Indian Institute of Technology 1971]
12.14 A 60 W-100 V tungsten lamp has a resistance of 20 at air temperature
(0 ◦ C). What is the rise in temperature of the filament under normal working conditions? The temperature coefficient of resistance of tungsten is
0.0052/ ◦ C.
[University of London]
12.15 A skeleton cube is made of wires soldered together at the corners of the cube,
the resistance of each wire being 10 . A current of 6 A enters at one corner
Fig. 12.11
541
12.10 A network of infinite resistors is shown in Fig. 12.10. Find the effective resistance of the network between terminal points A and B.
Fig. 12.10
12.11 What equal length of an iron wire and a constantan wire, each 1 mm diameter,
must be joined in parallel to give an equivalent resistance of 2 ? (resistivity
of iron and constantan are 10 and 49 μ cm, respectively).
[University of London]
12.12 A coil of wire has a resistance of 20 at 25 ◦ C and 25.7 at 100 ◦ C. Calculate the temperature coefficient.
[University of London]
12.13 A wire of resistance 0.1 /cm is bent to form a square ABCD of side 10 cm.
A similar wire is connected between the corners B and D to form the diagonal BD. Find the effective resistance of this combination between A and
C. A battery of negligible internal resistance is connected across A and C.
Calculate the total power dissipated.
[Indian Institute of Technology 1971]
12.14 A 60 W-100 V tungsten lamp has a resistance of 20 at air temperature
(0 ◦ C). What is the rise in temperature of the filament under normal working conditions? The temperature coefficient of resistance of tungsten is
0.0052/ ◦ C.
[University of London]
12.15 A skeleton cube is made of wires soldered together at the corners of the cube,
the resistance of each wire being 10 . A current of 6 A enters at one corner
Fig. 12.11