12th Physics ,Chapter-3 ( Current – Electricity )
(1) A charged particle has drift velocity 8.4 * 10 ^ – 4 * m * s ^ – 1 in electric fied of2.1 * 10 ^ – 10 Its mobility is:
a. 2.5 * 10 ^ 7 * m ^ 2 * V ^ – 1 * s ^ – 1
b. 4 * 10 ^ 6 * m ^ 2 * V ^ – 1 * s ^ – 1
c. 2.5 * 10 ^ – 7 * m ^ 2 * V ^ – 1 * s ^ – 1
d. 4 * 10 ^ – 6 * m ^ 2 * V ^ – 1 * s ^ – 1
Answer
(2) Kirchhoff’s loop rule is a direct consequence of law of conservation of:
a. Charge
b. Momentum
c. Angular Momentum
d. Energy
Answer
(3) For a conductor, which of the following relation is correct:
a. vec J = sigma vec E
b. vec J = vec E sigma
c. vec J = sigma vec E
d. None of these
Answer
(4) In current electricity, Ohm’s law is obeyed by all
a. Solids
b. Metals
c. Liquids
d. Gases
Answer
(5) The current of 3.2 A is flowing in a conductor. The number ofelectrons flowing per second will be
a. 2 * 10 ^ 9
b. 3 * 10 ^ 20
c. 5.2 * 10 ^ 19
d. 9 * 10 ^ 20
Answer
(6) Wheatstone bridge is used to measure
a. High resistance
b. Low resistance
c. Both high and low resistance
d. Potential difference
Answer
(7) Pure water is a of electricity:
a. bad conductor
b. good conductor
c. Insulator
d. none
Answer
(8) What is the order of drift velocity of electrons :
a. 10 ^ – 2 * m / s
b. 10 ^ – 3 * m / s
c. 10 ^ – 5 * m / s
d. none
Answer
(9) The number of electrons that constitute 1A of current are:
a. 6.25 * 10 ^ 16
b. 6.25 * 10 ^ 17
c. 6.25 * 10 ^ 18
d. 6.25 * 10 ^ 19
Answer
(10) What is called continuous flow of
electrons :
a. Electric current
b. Resistance
c. Conductivity
d. None
Answer
(11) Which instrument is used to measure electric current:
a. Voltmeter
b. Ammeter
c. Meter Bridge
d. None
Answer
(12) Electric current is scalar or vector :
a. vector
b. scalar
c. neither vector nor scalar
d. none
Answer
(13) What is produced, when electric current passes through a wire:
a. Heat
b. protons
c. photons
d. None
Answer
(14) What are the different methods for connecting resistance:
a. in series
b. in parallel
c. both (a) and (b)
d. none
Answer
(15) What is the condition for applying Ohm’s law:
a. conductor at constant temperature
b. conductor at law temperature
c. conductor at high temperature
d. none of these
Answer
(16) In what way a Voltmeter is connected in a circuit?
a. parallel
b. series
c. any where
d. none
Answer
(17) Filament of bulb is made of which metal:
a. sodium
b. steel
c. tungsten
d. none
Answer
(18) Two graphs are plotted between current (1) passing through a conductor and applied voltage (V) at two different temperature T_{1} & T_{2} We conclude that
a. T_{1} > T_{2}
b. T_{1} < T_{2}
c. T_{1} = T_{2}
d. T_{1} <= T_{2}
Answer
(19) A wire of resistance 12 is stretched to double its length. The resistance of the wire becomes:
a. 1 Ω
b. 1/4 * Omega
c. 20
d. 4 Ω
Answer
(20) Ohm’s law is valid when the temperature of the conductor is :
a. very low
b. very high
c. varying
d. constant
Answer
(21) The diameter of wire is doubled, its resistance will be:
a. half
b. doubled
c. for-times
d. one-fourth
Answer
(22) The unit of Electric current density is :
a. Am
b. A * m ^ 2
c. A * m ^ – 2
d. Am¹.
Answer
(23) Three resistances each of 3 ohms are connected to form atriangle, the resistance between any two terminals is
a. 1 Ω
b. 6 Ω
c. 2 Ω
d. 9 Ω
Answer
(24) The resistance of an ideal voltmeter is :
a. zero
b. ΙΚ Ω
c. infinite
d. 500 Ω
Answer
(25) If a wire is stretched by a force, it
a. increased
b. decreases
c. remain constant
d. None
Answer
(26) If temperature of a conductor increases, its conductivity :
a. increases
b. decreases
c. increases linearly
d. decreases linearly
Answer
(27) The unit for electrical conductivity is :
a. mho
b. mho-mtr
c. mho-mtr
d ohm-mtr
Answer
(28) Drift velocity of free electrons in a conductor does not depend upon its :
a. temperature
b. length
c. Area of cross-section
d. material con
Answer
(29) What is the S. I. unit of resistivity:
a. Ohm.m
b. Ohm¹ m-1
c. Ohm
d. None
Answer
(30) How resistance of a wire is affected by increasing its length:
a. resistance decreases
b. resistance increases
c. no effect
d. none
Answer
(31) A fuse wire is made of a wire of
a. low resistance and low melting point
b. high resistance and low melting point
c. low resistance and high melting point
d. high resistance and high melting point
Answer
(32) What is called the ratio of potential difference & current :
a. Resistance
b. Resistivity
c. Conduction
d. None
Answer
(33) What is the S. I. unit of resistance :
a. Ohm
b. Ohm.m
c. Ohm-m-l
d. None
Answer
(34) What is effect of increase in temperature on resistance of a conductor
a. resistance decreases
b. resistance increases
c. No effect
d. None
Answer
(35) Which one of the following is an anode in a dry cell:
a. zinc
b. carbon
c. copper
d. aluminium
Answer
(36) Which of the following cell can be recharged:
a. Voltaic cell
b. Daniel cell
c. fuel cell
d. dry cell
Answer
(37) A galvanometer can be converted into a voltmeter by connecting
a. a low resistance in series
b. a high resistance in parallel
c. a low resistance in parallel
d. a high resistance in series
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