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CBSE Questions for Class 12 Medical Physics Current Electricity Quiz 6 - MCQExams.com

A potential difference of 20V is needed to make a current of 0.05A  flow through a resistor. What potential difference is needed to make a current of 300 mA flow through the same resistor?
  • 60V
  • 120V
  • 40V
  • 150V
Kilowatt hour (kWh) represents the unit of :
  • power
  • impulse
  • momentum
  • energy
A cell of emf 5 V can supply a total energy of 9000 J, then the total charge that can be obtained from the cell would be _____ C
  • 180
  • 18000
  • 1800
  • 18
Power of an electric heater is 1000 W and it is running for 1 hour. Calculate the energy consumed by it
  • 3.6 MJ
  • 1.2 MJ
  • 1.8 MJ
  • 4.2 MJ
Electric current cannot flow through
  • Silver
  • Wood
  • Copper
  • None of these
State whether given statement is True or False
Silk threads are very good conductors.
  • True
  • False
The amount of work done (or, energy spent) by a source of power 1kW in 1h time is:
  • 1J
  • 1Wh
  • 1kWh
  • 1calorie
Convert 1 kWh to SI unit of energy.
  • 3.6×106J
  • 3.6×108J
  • 1.8×106J
  • 1.8×108J
Calculate the electric current in the circuit shown.
405265_69ebaf6483ea4949b5bb6606159993f7.png
  • 1.5A
  • 0.5A
  • 2.5A
  • 2A
Some matters do not allow the electricity to pass through it. What is called a matter which does not allow the electricity to pass though it?
  • Conductor
  • Insulator
  • Semiconductor
  • All of these
  • None of these
Two heater coils A and B made of the same material are connected in parallel across the same mains. The length and diameter of the wire used in A are doubled as that of the wire used in B. If H1 and H2 are the quantities of heat liberated per second in A and B, respectively, then H1:H2=
  • 1:4
  • 2:1
  • 1:3
  • 1:1
The substance which allows electric current to flow through it is called

  • Conductor
  • Insulator
  • Semiconductor
  • None of these
The current in the given circuit is
431140.png
  • 0.3\;\text{amp}
  • 0.4\;\text{amp}
  • 0.1\;\text{amp}
  • 0.2\;\text{amp}
Watt hour represents:
  • Electric energy
  • Current
  • Voltage
  • Power
Unit used in selling electrical energy to consumer is:
  • Volt-Ampere
  • Kilowatt-hour
  • Volt/second
  • None of these
An electric bulb of resistance 20   \Omega draws a current of 0.04   A. Calculate the potential difference at the ends.
  • 0.8 V
  • 2 V
  • 0.032 V
  • 5 V
Number of KWh in 1 Joule.
  • \displaystyle 3.6\times { 10 }^{ 6 }\ KWh
  • \displaystyle 2.77\times { 10 }^{ -7 }\ KWh
  • \displaystyle 600\ KWh
  • \displaystyle 1.6\times { 10 }^{ -19 }\ KWh
Which of these units of energy is the largest?
  • 1\ Calorie
  • 1\ Joule
  • 1\ Erg
  • 1\ Kilowatt-hour
Smallest commercial unit of energy is
  • Kilowatt hour
  • Watt second
  • Watt hour
  • Watt minutes
Energy consumed in our house has a unit of
  • watts
  • horse power
  • kilowatt-hours
  • none
Commercial unit of energy is .......................
  • Joule
  • Volt
  • Kilowatt hour
  • Watt second
Calculate the monthly bill if a heater of 100 watt is used at the rate of rs. 1 per unit for 1 hour daily.
  • Rs. 200
  • Rs. 6000
  • Rs. 100
  • Rs. 3
An electron in potentiometer with experiences a force 2.4 \times {10}^{-19}   N. The length of potentiometer wire is 6   m. The emf of the battery connected across the wire is (electronic charge = 1.6 \times {10}^{-19}   C)
  • 6 V
  • 9 V
  • 12 V
  • 15 V
Copper and Carbon wires are connected in series and the combined resistor is kept at \displaystyle { 0 }^{ \circ  }C. Assuming the combined resistance does not vary with temperature, the ratio of the resistances of Carbon and Copper wires at \displaystyle { 0 }^{ \circ  }C is:
 (Temperature coefficients of resistivity of Copper and Carbon respectively are \displaystyle 4\times { { 10 }^{ -3 } }/{ ^{ \circ  }{ C } } and \displaystyle -0.5\times { { 10 }^{ -3 } }/{ ^{ \circ  }{ C } })
  • 8
  • 6
  • 2
  • 4
The electric current i in the circuit shown is:
476007.png
  • 6\ A
  • 2\ A
  • 3\ A
  • 4\ A
This question relates to the DC circuit shown below.
The values for current, voltage, and resistance in the circuit are graphed from point A through point G in the graphs directly below.
Which of the graphs shows the voltage from point A to point G?

480188.jpg
  • A
  • B
  • C
  • D
  • E
A steady current flow in a metallic conductor of non-uniform cross-section. The quantity/quantities remaining constant along the whole length of the conductor is/are:
  • current, electric field and drift speed
  • drift speed only
  • current and drift speed
  • current only
Two cells A and B of emf 2V and 1.5 V respectively, are connected as shown in figure through an external resistance 10\Omega. the internal resistance of each cell is 5\Omega. The potential difference E_A and E_B across the terminals of the cells A and B respectively are:
461165.PNG
  • E_A = 2.0 V. E_B = 1.5 V
  • E_A = 2.125 V, E_B = 1.375 V
  • E_A = 1.875 V, E_B = 1.625 V
  • E_A = 1.875 V, E_B = 1.375 V
A meter bridge shown in fig.is balanced.what is the value of resistance X.
1566280_338941749bc4474da65b1a3ffd92a46f.png
  • 20 \Omega
  • 10 \Omega
  • 5 \Omega
  • 2.5 \Omega
In shown diagram, if voltage of battery is doubled and resistance kept constant then what is the new Power dissipated at resistor(Consider P was the initial power dissipation) ?

479418_f36c840b0e314ae0af3d95fee643e382.jpg
  • \dfrac{P}{4}
  • \dfrac{P}{2}
  • P
  • 2P
  • 4P
Potentiometer measures the potential difference more accurately than a voltmeter because :
  • it has a wire of high resistance
  • it has a wire of low resistance
  • it does not draw current from external circuit
  • it draws a heavy current from external circuit
A 2V battery, a990 \Omega resistor and a potentiometer of 2m length, all are connected in series of the resistance of potentiometer wire is 10\Omega, then the potential gradient of the potentiometer wire is
  • 0.05Vm^{-1}
  • 0.5Vm^{-1}
  • 0.01Vm^{-1}
  • 0.001Vm^{-1}
The circuit shows a battery and a variable resistor supplying power to a light circuit. As the variable resistor is moved towards left, the bulbs dim a little. What happens if the variable resistor is moved all the way to the right?

480826.jpg
  • The lights brighten considerably
  • The total circuit resistance increases
  • The total circuit current decreases
  • The total applied voltage increases
  • The total power used in the circuit increases
If current in a source of e.m.f. is in the direction of e.m.f., the energy of the source
  • Increase
  • Decrease
  • Remains constant
  • Zero
The five different colored graphs above represent different possible relationship between voltage across a resistor and current through the resistor.
Which of the graphs shows the correct relationship for a resistor that obeys Ohm's law?
498027.jpg
  • Red
  • Orange
  • Blue
  • Purple
What do you add to distilled water for making it to conduct electricity.
  • sulphuric acid
  • water
  • milk
  • base
In a potentiometer experiment of a cell of emf 1.25 V gives balancing length of 30 cm. If the cell is replaced by another cell, balancing length is found to be 40 cm. What is the emf of second cell?
  • \simeq 1.57 V
  • \simeq 1.67 V
  • \simeq 1.47 V
  • \simeq 1.37 V
Kirchoffs 1st and 2nd laws are based on conservation of
  • Energy and charge respectively
  • Charge and energy respectively
  • Mass and charge respectively
  • None of these above
A steady electric current is flowing through a cylindrical conductor.
  • The electric field at the axis of the conductor is zero.
  • The magnetic field at the axis of the conductor is zero.
  • The electric field in the vicinity of the conductor is zero.
  • The magnetic field in the vicinity of the conductor is zero.
Human body is a 
  • good conductor of electricity
  • poor conductor of electricity
  • semiconductor
  • good insulator
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
1 kilowatt hr = __________ joules.
  • 10.6 \times {10}^{6}
  • 3.6 \times {10}^{6}
  • 30.6 \times {10}^{6}
  • 3.6 \times {10}^{5}
 For driving current of 2A for 6 minute in a circuit. 1000 J of work is to be done. The e.m.f. of the source in the circuit is
  • 1.38V
  • 1.68V
  • 2.03V
  • 3.10V
Electromotive force represents
  • force
  • energy
  • energy per unit charge
  • current
Four bulbs marked 40W, \ 250V are connected in series with 250\ V mains, the total power consumed is
  • 10W
  • 40W
  • 320W
  • 160W
A potentiometer has a driving cell of negligible internal resistance. The balancing length of a Daniel cell is 5m. If the driving cell had internal resistance, the balancing length of the same Denial cell would have been
  • more
  • less
  • same
  • cannot be said from the data
Which of the following devices has a source of emf inside it?
  • Voltmeter
  • Ammeter
  • Ohm-meter
  • Rectifier
A battery of e.m.f. E has an internal resistance 'r'. A variable resistance R is connected to the terminals of the battery. A current I is drawn from the battery. V is the terminal P.D. lf R alone is gradually reduced to zero, which of the following best describes I and V?
  • I approaches E / r, V approaches E
  • I approaches infinity, V approaches E
  • I approaches zero, V approaches E
  • I approaches E / r, V approaches zero
1 Wh (Watt hour) is equal to :
  • 36\times { 10 }^{ 5 }J
  • 36\times { 10 }^{ 4 }J
  • 3600 J
  • 3600 { Js }^{ -1 }
 The figure shows in apart of an electric circuit, then the current I is
598120_c52f0c45b89e4edeac07bcc626a30068.png
  • 1 A
  • 3A
  • 2 A
  • 4 A
0:0:1


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