Physics Chapter 7 Entry test MCQs
51. The deviation of I-V graph from the straight line is due to:
a. Increase in temperature and increase in resistance
b. Decrease in temperature and decrease in resistance
c. Increase in temperature and decrease in resistance
d. Decrease in temperature and increase in resistance
52. The equivalent current which passes from a point at higher potential to a point at a lower potential as if it represented a movement of positive charges is
a. Electric current
b. Electronic current
c. Conventional current
d. Magnetic lines
53. The substances like germanium and silicon have
a. Negative temperature coefficient
b. Positive temperature coefficients
c. Both A and B
d. None of the above
54. If 2 A current passes through a resistor when connected to a certain battery. If the resistance is replaced by the double resistance, then the current will become
a. 4A
b. 2A
c. 1A
d. 6A
56. Electric charge on an object is measured as 5 micro coulombs. How the value of this charge can be expressed in terms of base unit:
a. 5 x 10 ampere second
b. 5 x 10-3 ampere second
c. 5 x 10-2 ampere second
d. 5 x 10-6 ampere second
57. 12 volt battery is applied across 62 resistance to have a steady flow of current. What must be the required potential difference across the same resistance to have a steady current of one ampere?
a. 3.V
b. 12V
c. 6.V
d. 1V
58. Resistance between two opposite faces of square thin film of area 1mm2 having thickness of 1µm if resistivity of material is 10-6 Omega*m will be:
a. 100 Ω
b. 1000 Ω
c. 10 Ω
d. 1Ω
59. If the potential difference across a resistor is doubled:
a. Only the resistance is doubled
b. Only the current is doubled
c. Only the resistance is halved
d. Only the current is halved
60. A total charge of 100 C flows through a 12W bulb in a time of 50 second. What is the potential difference across the bulb during this time?
a. 6.0V
b. 0.12V
c. 24V
d. 2.0V
61. The temperature coefficient of resistance of a semiconductor is:
a. Imaginary
b. Positive
c. Zero
d. Negative
62. 2 x 106 electrons passing through a conductor in 1 ms. Find electric current flowing through conductor:
a. 320 x 10-10A
b. 32 x 10-9 A
c. 0.32 x 10-10A
d. 3.2 x 10-10A
63. A carbon resistor is connected to a battery of 50volt and 2ampere through it. If voltage is increased to 75volt, the current will become: current is passing
a. 1.5Amp
b. 3Amp
c. 6Amp
d. 4.5Amp
64. When the current is neither drawn from a source nor given to it then:
a. E = V1
b. E > V1
c. V1 > E
d. Both B”&”C”
65. When potential difference is applied across the ends of uniform wire of length / and radius r, a current I flow in the wire. If same potential difference is applied to the ends of another wire of the same material but of length 2/ and radius 2r, the current in the wire is
a. 2l
b. 1/4
c. 1/2
d. I
66. The reciprocal of the conductance is called
a. Resistance
b. conductivity
c. Inductance
d. Resistivity
67. A typical mobile phone of 5.0 V and an internal resistance of 200 m 2. What is the terminal P.D of the battery when it supports a current of 500 mA?
a. 5.0 V
b. 4.8V
c. 5.1V
d. 4.9V
68. A metal cube with sides of length “a” has electrical resistance R between opposite faces. What is the resistance between the opposite faces of a cube of the same metal with sides of length 3a?
a. R/3
b. 9R
c. R/9
d. 3R
69. A filament lamp has a resistance of 180Ω when the current in it is 500mA. What is the power dissipated in the lamp?
a. 290 W
b. 45W
c. 360 W
d. 90 W
70. A cell of internal resistance 2.0Ω and electromotive force (e.m.f) 1.5V is connected to a resistor of resistance 3.0Ω what is the potential difference across 3Ω resistor.
a. 0.9 V
b. 5V
c. 0.6V
d. 1.2V
71. Calculate the rate at which energy is transferred by 220 V mains supply which provides a current of 0.1 A to a LED?
a. 2.2 kW
b. 22 kW
c. 2.2 W
d. 22 W
72. A copper wire has length L and cross-sectional area A. Its resistance is R. If we halved the length and halved the diameter of wire, then what will be the resistance of this wire?
a. 3R
b. R
c. 4R
d. 2R
73. A car battery has EMF of 12 Volts and internal resistance 5 x 10-2 ohm. If it draws 60 ampere current, then terminal voltage of the battery will be
a. 15 volts
b. 5 volts
c. 9 volts
d. 3 volts
74. One kilowatt-hour is commonly termed as one commercial unit of electric energy which is equal to
a. 3.6 x 104 j
b. 3.6 x 105 j
c. 3.6 x 103 j
d. 3.6 x 106 j
75. When a wire is compressed and its radius becomes 2R then its resistance will be:
a. 1/16 R
b. 16R
c. 1/4 R
d. 4R