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CBSE Questions for Class 12 Medical Physics Current Electricity Quiz 3 - MCQExams.com

SI unit of electrical energy is
  • Joule
  • Kilowatt hour
  • KiloJoule
  • Watt hour
When does two elements are said to be in series?
  • When same current physically flows through both elements
  • When different current physically flows through both elements
  • When no current physically flows through both elements
  • None of these
Electromotive Force (EMF) may be defined as:
  • work done per coulomb on the charge.
  • drift velocity of electrons.
  • flow of electron.
  • the number of coulombs of charge per second.
Consider the following two statements:
1) Kirchoff's junction law follows from the conservation of charge
2) Kirchoff's loop law follows from the conservation of energy. 
Which of the following is correct?
  • both 1 and 2 are wrong
  • 1 is correct and 2 is wrong
  • 1 is wrong and 2 is correct
  • both 1 and 2 are correct
Which of the following is not a correct statement with respect to the given circuit?
591609.png
  • Switch S is closed
  • Current is flowing in the circuit
  • B and C are connected in series
  • A is connected in series to B and C
Your are given three equal resistances. In how many combinations can they be arranged?
  • Three
  • Four
  • Five
  • Two
Which of the following component is connected in parallel in the circuit?
591599.png
  • Rheostat
  • Capacitor
  • Bulb
  • LED
Which of the following methods does not help to minimize the error due to contact resistance in Wheatstone's meter bridge experiment:
  • The wire used must be uniform
  • The wire used must be non-uniform
  • Null point is obtained near the middle of the wire
  • Interchange the positions of unknown resistance (X) and known resistance(R)
For a metallic wire, the ratio Vi (where, V = applied potential difference and i = current flowing)
  • is independent of temperature
  • increases as the temperature rises
  • decreases as the temperature rises
  • increases or decreases as temperature rises depending upon the metal.
Kirchhoff's law of junction, I=0, is based on
  • Conservation of energy
  • Conservation of charge
  • Conservation of energy as well as charge
  • Conservation of momentum
 Potentiometer measures potential more accurately because
  • it measures potential in the open circuit .
  • it uses sensitive galvanometer for null deflection .
  • it uses high resistance potentiometer wire .
  • it measures potential in the closed circuit .
A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is /are
  • current , electric current and drift velocity
  • drift speed only
  • current and drift speed only
  • current only
Which of the following statements are true?
  • During electrolysis, charge flows through electrolytic solution via electrons
  • The randomly moving electrons in a metal wire will start moving in a particular direction when a potential difference is applied across it
  • A negatively charged particle has higher electric potential than a positively charged particle
  • Charge flows only through negative charge carriers like electrons
State whether given statement is True or False
In conductors, the innermost electrons are free to move :
  • True
  • False
What happens when negative terminal of cell is connected to other negative terminal of cell in a particular circuit?
  • Current will not flow in circuit
  • Current will flow in circuit
  • temperature of cell will increase
  • cell gets damaged
Kirchoff's junction law is equivalent to ___________.
  • Conservation of energy
  • Conservation of charge
  • Conservation of electric potential
  • Conservation of electric flux
Materials that allow electrons to flow through them are known as
  • Insulator
  • Conductors
  • Electrolytes
  • Bases
State whether given statement is True or False
The wire of potentiometer is made up of Aluminium.
  • True
  • False
Why is electrical wiring usually made from copper?
  • Because copper is shiny.
  • Because copper conducts electricity.
  • Because copper is not magnetic
  • none of these
Which of the following has negative temperature coefficient of resistance?
  • Copper
  • Aluminium
  • Iron
  • Germanium
A potentiometer can be used to measure
  • emf of newly desined cell
  • internal resistance of a cell
  • unknown resistance
  • potential difference across a resistor
Identify the correct way to connect cells to make battery.
  • None of the above
If the length of potentiometer wire is increased, then the length of the previously obtained balance point will
  • Increase
  • Decrease
  • Remains unchanged
  • Becomes two times
The value of I in the figure shown below is
638057_e289083fc0d445f58cc6f89d79f72bc1.png
  • 19A
  • 21A
  • 8A
  • 4A
A cell of emf 6 V and resistance 0.5 ohm is short circuited. The current in the cell is 
  • 3 amp
  • 12 amp
  • 24 amp
  • 6 amp
The current in a car headlamp is 3.0A when connected to a 12V battery. What is the resistance of the lamp when it is lit?
  • 0.25Ω
  • 4.0Ω
  • 15Ω
  • 36Ω
Write true or false for the following statements :
Electric power is also called BOTU. 
  • True
  • False
The given circuit is part of a certain circuit. The current through resistors are shown. The potential difference VPVQ is
1503291_9b6edd1a67904fda982b9f7b70ed406d.png
  • 2V
  • 19V
  • 22V
  • 19V
The Kirchhoff's first law (i=0) and second law (iR=E) , where the symbols have their usual meanings, are respectively based on :
  • Conservation of charge, conservation of momentum
  • Conservation of energy, conservation of charge
  • Conservation of momentum, conservation of charge
  • Conservation of charge, conservation of energy
A wire has a diameter of 0.2mm and a length of 50cm. The specific resistance of it's material is 40×106ohmcm. The current through it, when a potential difference of 2V is applied across it, is
  • 3.14A
  • 31.4A
  • 0.314A
  • 0.0314A
In a potentiometer whose wir   e resistance is 10Ω the potential fall per cm is V volts. To reduce it to V/4  Volt cm1, the resistance that must be connected in series with the potentiometer wire is
  • 40Ω
  • 30Ω
  • 20Ω
  • 10Ω
The resistance of a wire is 5 ohm at 50C and 6 ohm at 100C. The resistance of the wire at 0C will be:
  • 2 ohm
  • 1 ohm
  • 4 ohm
  • 3 ohm
A carbon filament has resistance of 120Ω at 00C. The resistance of a copper filament connected in series with carbon so that the combination has same resistance at all temperatures must be
α of carbon =7×104/0C; α of copper =4×103/0C
  • 120Ω
  • 21Ω
  • 60Ω
  • 210Ω
n identical cells, each of internal resistance (r) are first connected in parallel and then connected in series across a resistance (R). If the current through R is same in both the cases then: 
  • R=r/2
  • r=R/2
  • R=r
  • r=0
Assertion : The equivalent resistance between the points X and Y in the figure is 10.
Reason : According to Wheatstone bridge, points A and C have the same potential.

424.jpg
  • Both (A) and (R) are true and (R) is the correct explanation of A
  • Both (A) and (R) are true but (R) is not the correct explanation of A
  • (A) is true but (R) is false
  • (A) is false but (R) is true
The resistance of a bulb filament is 100Ω at a temperature of 1000C. If its temperature coefficient of resistance be 0.005 per 0C , its resistance will become 200Ω at a temperature of :
  • 3000C
  • 4000C
  • 5000C
  • 2000C
In a potentiometer of ten wires, the balance point is obtained on the sixth wire. To shift the balance point to eighth wire, we should
  • increase resistance in the primary circuit.
  • decrease resistance in the primary circuit.
  • decrease resistance in series with the cell whose e.m.f. has to be measured.
  • increase resistance in series with the cell whose e.m.f. has to be measure.
A potentiometer wire 10 m long has a resistance of 40Ω. It is connected in series with a resistance box and a 2V storage cell. If the potential gradient along the wire is 0.1 mV/cm ,  the resistance in the box is
  • 760Ω
  • 260Ω
  • 1060Ω
  • 960Ω
The current that passes through 20 ohm resistance when it is connected in parallel with a 30 ohm resistance and this set is connected to a battery of 2V is
  • 0.2A
  • 0.3A
  • 0.1A
  • 0.016A
The temperature coefficient resistivity of a material is 0.0004/K. When the temperature of the material is increased by 50oC, its resistivity increases by 2×108 ohmmeter.The initial resistivity of the material of the resistance
  • 50×108
  • 90×108
  • 100×108
  • 200×108
The potentiometer is more appropriate for measuring potential difference than a voltmeter because
  • the resistance of voltmeter is high
  • the sensitivity of a potentiometer is higher than that of voltmeter
  • the resistance of potentiometer wire is very low
  • the potentiometer does not draw any current from the unknown source of emf
Resistance of a resistor at temperature t0C is Rt=R0(1+αt+βt2). Here R0 is the resistance at 00C. The temperature coefficient of resistance at temperature t0C is
  • (1+αt+βt2)α+2βt
  • α+2βt
  • α+2βt(1+αt+βt2)
  • α+2βt2(1+αt+βt2)
Four conductors of resistance 4, 3, 9 and 6 ohm are connected in AB,BC, CD and DA arms of a Wheatstone bridge. The bridge can be balanced by connecting.

  • 1) 6 ohm in series with 3 ohm conductor
  • 2) 4 ohm in parallel with 6 ohm conductor
  • 3) 3 ohm in series with 3 ohm conductor
  • 4) 5 ohm in series with 6 ohm conductor
Aluminium(α=4×103K1)  resistance of 60Ω and carbon (α=0.5×103K1) resistance 40Ω are connected in parallel. The combination is heated. The effective resistance is

  • Greater than 24Ω
  • Less than 24Ω
  • Greater than 40Ω
  • Greater than 100Ω
If in a Wheatstone bridge the battery and Galvanometer are interchanged, the condition for balance
  • is disturbed
  • is not disturbed
  • depends on the internal resistance of the bridge
  • depends on the values of the resistances in the bridge
The resistance of a metallic conductor increases with temperature due to:
  • change in carrier density
  • change in dimension of the conductor
  • increase in the number of collisions among the carriers
  • increase in the rate of collisions between the carriers and the vibrating atoms of the conductor.
Consider a thin square sheet of side L and thickness t, made of a material of resistivity ρ. The resistance between two opposite faces, shown by the shaded areas in the figure is____
42336.PNG
  • directly proportional to L
  • directly proportional to t
  • independent of L
  • independent of t
Consider a long conductor, the middle of which is earthed. If the potential difference across the two ends of the conductor is 220 V, then what is the potential at the ends and the middle point?
  • 220 V all over the conductor
  • 110 V and 110 V at ends and 0 V at the mid point
  • 0 V at ends and 220 V at midpoint
  • 220 V all over the conductor
The length of a potentiometer wire is l. A cell of emf E is balanced at a length L/3 from the
positive end of the wire. If the length of the wire is increased by L/At what distance will the
same cell give a balance point.

  • 2L3
  • L2
  • L6
  • 4L3
A wheel having mass m has charges +q and q on diametrically opposite points. It remains in equilibrium on a rough inclined plane in the presence of uniform vertical electric field E =


41401.jpg
  • μgq
  • μg2q
  • μgtanθ2q
  • None of these
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Practice Class 12 Medical Physics Quiz Questions and Answers