Q.1The resistivity of a metal wire is
10 x 10−8 Ω m at 20°C. Find the resistance of the same wire of 2 meter length
and 0.3 mm thickness.
Q.2The
resistance of an electric wire of an alloy is 10 Ω. If the diameter of wire is
0.001
meter, and length is 1 m, find its resistivity.
Q.3What
will be the resistivity of a metal wire of 2 m length and 0.6 mm in diameter,
if the resistance of the wire is 50 Ω.
Q.4The
area of cross section of wire becomes half when its length is stretched to
double. How the resistance of wire is affected in new condition?
Q.5Calculate
the resistance of a copper wire of length 2m and area of cross section 10-6 m².
Resistivity of copper is 1.7 x 10-8 Ωm
Q.6Resistivity
of a given copper wire of length 2m is 1.7 x 10-8 Ωm. The wire is stretched so
that its length becomes 4m. Find new resistivity of the copper wire.
Q.8A
piece of wire of resistance 20Ω is drawn out so that its length is increased to
twice its original length Calculate the resistance of the wire in the new
situation
Q.9
Two wires of the same metal have same length, but their cross-sections are in
the ratio 3 : 1. They are joined in series. The resistance of thicker wire is
10 Ω. What will be the total resistance of the combination?
Q.10If
a person has five resistors each of value 15 Ω, then the maximum
resistance
he can obtain by connecting them is
Q.11The
maximum resistance which can be made using four resistors each of 2 Ω
Q.12Show
how would you join three resistors, each of resistance 9 Ω so that the
equivalent resistance of the combination is (i) 13.5 Ω, (ii) 6 Ω
Q.13Two
bulbs of 100 W and 40 W are connected in series. The current through
the
100 W bulb is 1 A. The current through the 40 W bulb will be.
Q.14Three 2 Ω resistors A,
B and C are connected in such a way that the total resistance of the
combination is 3 Ω. Show the arrangement of the three resistors and justify
your answer.
Q.15An electric iron has a
rating of 750 W; 200 V. Calculate:
(i) the current required.
(ii) the resistance of its
heating element.
(iii) energy consumed by
the iron in 2 hours.
Q.16Two bulbs have ratings 100 W, 220 V
and 60 W, 220 V respectively. Which
one has a greater resistance?
Q.17 potential difference between the
terminals of an electric heater is 60 V when it draws a current of 4 A from the
source. What current will the heater draw if the potential difference is
increased to 120 V
Q.18current of 0.2 Ampere flows through a
conductor of resistance 4.5 Ω. Calculate the potential difference at the ends
of the conductor.
In the circuit shown below,
if ammeter read 1A, then find the value
of unknown resistance X
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