1. 5 amperes of current is passed through a metallic
conductor. The charge flowing in one minute in
coulombs will be
a) 5
b) 12
c) 1/2
d) 300
Explanation:
2.Two wires of the same material are given. The
first wire is twice as long as the second and has
twice the diameter of the second. The resistance
of the first will be
a) Twice of the second
b) Half of the second
c) Equal to the second
d) Four times of the
second
Explanation:
3.An electric wire is connected across a cell of
e.m.f. E. The current I is measured by an
ammeter of resistance R. According to ohm's law
a) \[E=I^{2}R\]
b) \[E=IR\]
c) \[E=R/I\]
d) \[E=I/R\]
Explanation: \[E=IR\]
4. The resistances of a wire at temperatures \[t^{\circ}C\] and \[0^{\circ}C\] are related by
a) \[R_{t}=R_{0}\left(1+\alpha t\right)\]
b) \[R_{t}=R_{0}\left(1-\alpha t\right)\]
c) \[R_{t}=R_0^2\left(1+\alpha t\right)\]
d) \[R_{t}=R_0^2\left(1-\alpha t\right)\]
Explanation: \[R_{t}=R_{0}\left(1+\alpha t\right)\]
5. An electric wire of length ‘I’ and area of crosssection
a has a resistance R ohms. Another wire
of the same material having same length and area
of cross-section 4a has a resistance of
a) 4 R
b) R/4
c) R/16
d) 16 R
Explanation:
6.For which of the following the resistance
decreases on increasing the temperature
a) Copper
b) Tungsten
c) Germanium
d) Aluminium
Explanation: For semiconductors, resistance decreases on increasing the temperature.
7. If \[n,e,\tau\] and m respectively represent the density,
charge relaxation time and mass of the electron,
then the resistance of a wire of length l and area
of cross-section A will be
a) \[\frac{ml}{ne^{2}\tau A}\]
b) \[\frac{m\tau^{2} A}{ne^{2}l}\]
c) \[\frac{ne^{2}\tau A}{2ml}\]
d) \[\frac{ne^{2} A}{2m\tau l}\]
Explanation:
8. The relaxation time in conductors
a) Increases with the increase of temperature
b) Decreases with the increase of temperature
c) It does not depend on temperature
d) All of sudden changes at 400 K
Explanation:
9. Which of the following statement is correct
a) Liquids obey fully the ohm's law
b) Liquids obey partially the ohm's law
c) There is no relation between current and p.d.
for liquids
d) None of the above
Explanation: In VI graph, we will not get a straight line in case of liquids.
10.The resistance of a wire is 10 Ω . Its length is
increased by 10% by stretching. The new
resistance will now be
a) 12 Ω
b) 1.2 Ω
c) 13 Ω
d) 11 Ω
Explanation:
