a wire of uniform cross section and of resistance 10 ohm is cut into two equal parts. the two pieces are then twisted around each other.what will be the new resistance of wire ? explain also. if know the answer then only answer it's urgent...
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A uniform wire of resistance R and length L is cut into four equal parts, each of length L/4 which are then connected in parallel combination. The effective resistance of the combination will be?
Ans
Resistance of a wire =
A
ρl
where, ρ is the resistivity of material of wire
l is length of wire
A is the cross sectional area of the wire.
⇒R=
A
ρl
⇒
A
ρ(L/4)
=
4
R
Thus, the four smaller wires have resistance R/4 each.
Now, these four resistances are connected in parallel.
Thus, effective resistance R
eff
is given by
⇒
R
eff
1
=
R/4
1
+
R/4
1
+
R/4
1
+
R/4
1
⇒R
off
=
16
R
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