Q.1
A steady current is passing through a linear conductor of non-uniform cross-section. The current density in the conductor is
  • a) independent of area of cross section
  • b) directly proportional to area of cross section
  • c)inversely proportional to area of cross section
  • d)inversely proportional to square root of area of cross section
Q.2
If a copper wire is stretched to make its radius decrease by 0.1%, then the percentage in increase in resistance is approximately
  • a) 0.1 %
  • b) 0.2%
  • c) 0.4%
  • d) 0.8%
Q.3
The resistance of wire of length L and diameter D is RΩ. The wire is stretched to reduce its diameter to one third. The resistance of the wire will now be
  • a)R/9
  • b) 9R
  • c)R/81
  • d)81R
Q.4
Two wires of equal length and of material x and y have same resistance. The ratio of the radii of the two wire is 1:The ratio of the specific resistance of the two material is
  • a) 1:1
  • b) 1:2
  • c)1:4
  • d)4:1
Q.5
Two wires of 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
Q.6
A copper wire and aluminum wire of same length have same resistance. Specific resistance of aluminum is more than that of copper. Which of the following statement is correct
  • a) Mass of copper and aluminum wire is same
  • b) Mass of copper wire is more than that of aluminum wire
  • c) Mass of copper wire is less than that of aluminum wire
  • d) Nothing can be said about the relative mass of the two wires as information given is incomplete
Q.7
A steady current is passing through linear conductor of non-uniform cross-section. The current in the conductor is
  • a)independent of area of cross section
  • b) directly proportional to length of conductor
  • c)directly proportional to the area of cross-section
  • d)inversely proportional to the length of the conductor
Q.8
The quantity in electricity analogues to friction in linear mechanical motion is
  • a) resistance
  • b) potential
  • c)charge
  • d)induction
Q.9
When current passes through a conductor a the heat produced due to
  • a) fall of electrons from higher energy orbit to lower energy orbit
  • b) Inter atomic collisions
  • c)Inter electron collisions
  • d)collision of electrons with atoms
Q.10
The number of free electrons per unit volume in copper is n. the electrons, each of charge q are flowing systematically along the length of the wire with velocity v and constitute an electric current I. If the area of cross-section of the wire is A, the current density in the wire is
  • a) nAq/v
  • b) nq/v
  • c) nAqv
  • d) nqv
Q.11
Two wires A and B are made of copper. Both wires are 1 metre long but wire A is 1mm thick and wire B is 2mm thick. The specific resistance is
  • a)more for A
  • b) more for B
  • c)same for both A and B
  • d)can not be compared
Q.12
Through a wire of resistance 4Ω a charge of 12C is passing in 2 minutes. The potential difference across the wire is
  • a) 0.4 V
  • b) 1.5 V
  • c)0.667V
  • d)24 V
Q.13
The electric intensity E, Current density J and Specific resistance ρ are related to each other through the relation
  • a) E = J ρ
  • b) E = Jρ
  • c) E = ρ/J
  • d) ρ = JE
Q.14
If copper wire is stretched to make it 0.1 % longer, the the percentage change in resistance is approximately
  • a)0.1%
  • b) 0.2%
  • c)0.4%
  • d)0.8%
Q.15
When a potential difference V is applied across a conductor at temperature T, the drift velocity of electrons is proportional to
  • a) √T
  • b) V0
  • c)√V
  • d)V
Q.16
You have three equal resistance's. How many different combinations can you have with these resistance's
  • a) 2
  • b) 3
  • c) 4
  • d) 6
Q.17
All of the following statements are true, except:
  • a)conductance is the reciprocal of resistance and is measured in sidemen
  • b) Ohm's law is not applicable at very low and very high temperatures
  • c)Ohm's law is applicable to semiconductors
  • d)Ohm's law is not applicable to electron tubes, discharge tubes and electrolytes
Q.18
The electric current in a discharge tube containing a gas is due to
  • a) electrons only
  • b) positive ions only
  • c)negative ions and positive ions both
  • d)electrons and positive ions both
Q.19
The quantity in electricity analogous to temperature is
  • a) resistance
  • b) potential
  • c)charge
  • d)inductance
Q.20
In figure potential difference between point x and y is
ch-14_que_no-288_img_no1.png
  • a) 10 V
  • b) 5 V
  • c) 15 V
  • d) 8.33 V
Q.21
Two wire of same length and material have their cross-sections in the ratio of 1:The two wires are joined so that their ends fuse into one another without any other change. The ratio of the resistance of the fused wire and the wire of smaller cross-section is
  • a) 1:3
  • b) 1:4
  • c) 1:2
  • d) 4:1
Q.22
(1) The product of a volt and coulomb is a Joule (2) The product of a volt and an ampere is Joule/sec (3) the product of volt and watt is horse power (4) watt-hour can be measured in terms of electron -volts
  • a) all the four are correct
  • b) (1) and (2) and (4) are correct
  • c)(1) and (3) are correct
  • d)(3( and (4) are correct
Q.23
Assume that each atom of copper contributes one free electron. If the current flowing through a copper wire of 1mm diameter is 1.1 ampere, the drift velocity of electrons will be [ density of copper=9 gm/cm3 and atomic weight of copper=63]
  • a) 0.3 mm/sec
  • b) 0.1 mm/sec
  • c) 0.5 mm/sec
  • d) 0.2 mm/sec
Q.24
Overloading of an electric circuit implies
  • a) drawing of large current
  • b) connecting high resistance device
  • c)connecting a number of electric devices in series with the power supply
  • d)none of the above
Q.25
Two conductor are made of the same material and have same length. Conductor A is solid wire of diameter 1mm. Conductor B is hollow tube of outer diameter 2 mm and inner diameter 1mm. The ratio of resistance RA to RB
  • a) 3:1
  • b) 1:3
  • c)1:1
  • d)2:1
Q.26
The temperature of metal wire rises when an electric current passes through it because
  • a) collision of conduction electrons with each other releases heat energy
  • b) collision of conduction electrons with atoms of the metal gives them energy which appears as heat
  • c) when the conduction electrons fall from higher energy level to a lower energy level, heat energy is released
  • d) heat energy is released when the conduction electrons are separated from their parent atoms
Q.27
Which of the following can be used to express energy? Symbols have usual meaning for the units of physical quantities (1) kWh (2) VC (3) VAs2 (4) A2Ωs2
  • a)All of above
  • b) (1), (2), (3)
  • c)(3), (4)
  • d)(1), (2)
Q.28
A current I flows in a wire of circular cross-section with the free electrons travelling with a drift velocity v. What is the drift velocity of electrons when a current 2I flows in another wire of twice the radius and of the same material
  • a) v / 4
  • b) v / 2
  • c)v
  • d)2v
Q.29
Two wires of same material have same length. Their resistance's are proportional to
  • a) 1 / masses of the wires
  • b) square of masses of the wires
  • c)masses of the wires
  • d)cube of masses of the wires
Q.30
A steady current i passes through a linear conductor of uniform cross-section. Any given segment of the conductor has
  • a) A net negative charge
  • b) a net positive charge
  • c) a zero net charge of any kind
  • d) a net charge proportional to the volume of the segment
0 h : 0 m : 1 s