YASH CLASSES
10. ELECTRIC CURRENT
85. What length
of a copper wire
of cross
section area
0.01 mm 2 would be required
to obtain
a resistance of 1 kΩ . Resistivity
of
copper 1.7 x 10 -8 Ωm .
ELECTRICITY
86. What length of a iron wire
of cross
section
area 0.05 mm 2 would
be required
to
obtain a resistance
of 2 kΩ
. Resistivity
of
iron 10 x 10 -8 Ωm .
87. What length of a aluminium
wire of cross
section
area 0.02 mm 2 would
be required
to
obtain a resistance
of 2.5 kΩ . Resistivity
of
aluminium 2.63 x 10 -8 Ωm .
88. What
length of a copper
wire of cross
section
area 0.03 mm 2 would
be required
to
obtain a resistance
of 1.8 kΩ
. Resistivity
of
copper 1.7 x 10 -8 Ωm .
89. Derive an expression
for the equivalent
resistance
of three resistance connected
in series.
90. Derive
an expression for
the equivalent
resistance
of three resistance connected
in parallel.
91. A piece
of wire having a resistance R
is cut
into
four equal parts .
a. how does
the resistance of each part
compare
with
the original resistance ?
b. when connect in parallel find
resistance
compare
with original resistance .
c. two connected in series and
two connected
in
parallel compare with
original resistance .