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.
  • $$3.6\times 10^6J$$
  • $$3.6\times 10^8J$$
  • $$1.8\times 10^6J$$
  • $$1.8\times 10^8J$$
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 $$H_1$$ and $$H_2$$ are the quantities of heat liberated per second in $$A$$ and $$B$$, respectively, then $$H_1 : H_2 =$$
  • $$1 : 4$$
  • $$2 : 1$$
  • $$1 : 3$$
  • $$1 : 1$$
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, a$$990 \Omega$$ 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


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Medical Physics Quiz Questions and Answers