Current Electricity – Multiple Choice Questions

Q1. When Wheatstone bridge is in balance condition, the current through galvanometer will be

  • Maximum
  • Minimum
  • Zero
  • Depends upon the type of galvanometer.

Q2. Three resistors of 4 Ω, 12 Ω, and 6 Ω are connected in parallel. No. of 12 Ω resistors required to be connected in parallel to reduce the total resistance to half of its original is

  1. 2
  2. 3
  3. 6
  4. 12

Q3. There are n cells in a circuit. Each cell is of emf 1.5 V and has internal resistance of 0.5 Ω. When they are connected in series with a resistance of 20 Ω, they send a current of 0.6 A through the circuit. What is the value of n?

  1. 5
  2. 10
  3. 15
  4. 20

Q4. A circuit has 5 A current flowing through it. When an additional resistance of 2 Ω is inserted in the circuit, the current through it drops to 4 Ω. What is the initial resistance of the circuit?

  1. 4 Ω
  2. 2 Ω
  3. 8 Ω
  4. 16 Ω

Q5. Ohm’s law states that

  1. V = I/R
  2. V = R/I
  3. V = IR
  4. V = I2R

Q6. The type of materials whose resistivity is affected on adding the impurity is known as

  1. Conductor
  2. Insulator
  3. Semiconductor
  4. Iron alloys

Q7. The current in a coil of resistance 90 ohms is to be reduced by 90 percent. What value of resistance should be connected in parallel with it?

  1. 9 Ω
  2. 100 Ω
  3. 90 Ω
  4. 10 Ω

Q8. Copper is not used as potentiometer wire because

  1. Copper is soft and flexible
  2. Copper has high temperature coefficient of resistance and small resistivity
  3. Copper has high resistivity
  4. Copper has low temperature coefficient of resistance

Q9. Which of the following is an ohmic conductor?

  1. diode
  2. LED
  3. Thyristor
  4. Metal conductor

Q10. Three equal resistors each of resistance r are connected to form a triangle. The equivalent resistance across any two corners of the triangle is

  1. 2r
  2. r/3
  3. 2r/3
  4. 3r

Q11. Wheatstone bridge is used to measure

  1. emf
  2. potential
  3. resistance
  4. current

Q12. Two cells of 1.25 V and 0.75 V are connected in parallel. The effective voltage will be

  1. 0.75 V
  2. 1.25 V
  3. 2.00 V
  4. 0.5 V

Q13. A resistance of 2 Ω is connected a across the gap of a metre-bridge (the length of the wire is 100 cm) and an unknown resistance,

x > 2 Ω, is connected across the other gap. The balance point is noticed at l cm from the positive end of the battery.  When these resistances are interchanged, the balance point shifts by 20 cm. Neglecting any correction, the unknown resistance is:

  1. 3 Ω
  2. 4 Ω
  3. 5 Ω
  4. 6 Ω

Q14. What is the maximum current that can be drawn from a cell of emf E and internal resistance r connected to an external resistance R?

  1. I = E/r
  2. I = E/R
  3. I = E/(R+r)
  4. infinite

Q15. Two identical cells are connected in series and then in parallel. When connected it series they send a current of 10 A through a 5 Ω resistor and when connected in parallel they send a current of 8 A. What is the internal resistance of each cell?

  1. 2.5 Ω
  2. 5 Ω
  3. 7.5 Ω
  4. 10 Ω

Q16. 1 ohm is equal to

  1. 1 ampere per volt
  2. 1 volt per ampere
  3. 1 milliampere per volt
  4. 1 ampere per millivolt

Q17. Three identical cells, each of 2V and internal resistance of 0.2 ohm are connected in series to an external resistance of 7.4 ohm. The current in the circuit will be

  1. 0.75 A
  2. 1.05 A
  3. 2 A
  4. 3 A

Q18. When the position of cell and galvanometer in a Wheatstone bridge is inter-changed, its balanced condition

  1. Changes
  2. Remains unchanged
  3. Changes and it depends on cell position only
  4. Changes and depends on galvanometer position only

Q19. The total resistance of three parallel resistors is

  1. RT = 1/R1 + 1/R2 + 1/R3
  2. RT = R1 + R2 + R3
  3. 1/RT = 1/R1 + 1/R2 + 1/R3
  4. 1/RT = R1 + R2 + R3

Q20. While traversing a loop we must consider

  1. resistors and sources of emf
  2. only resistors
  3. only sources of emf
  4. none of the above

Q21. If a wire of resistivity ρ is stretched to double its length. Then its new resistivity will be

  1. half of the original resistivity
  2. Four times the original resistivity
  3. Double the original resistivity
  4. Remains same

Q22. Three identical cells, each of 4 V and internal resistance r, are connected in series to a 6 ohm resistor. If the current flowing in the circuit is 2 A. The internal resistance of each cell is

  1. 0.11 ohm
  2. 0 ohm
  3. 0. 12 ohm
  4. 1.1 ohm

Q23. If a wire of resistivity ρ is stretched to double its length. Then its new resistivity will be

  1. half of the original resistivity
  2. Four times the original resistivity
  3. Double the original resistivity
  4. Remains same

Q24. The resistance of a wire is r ohms. It is stretched to double its length. The new resistance of the wire in ohms is

  1. r/2
  2. 2r
  3. r/4
  4. 4r

Q25. Mobility of charge carriers in a conductor is given by

  1. drift velocity/ electric field
  2. (drift velocity)(electric field)
  3. ( charge of an electron).drift velocity/ electric field
  4. mass of an electron.(drift velocity/ electric field)

Q26. An electric bulb is rated 220 V and 100 W. Power consumed by it operated on 110 V is

  1. 25 W
  2. 50 W
  3. 75 W
  4. 90 W

Q27. In a potentiometer a cell of e.m.f 2V gives a balance point at 30cm. If the cell is replaced by another cell and the balance point shifts to 60cm.What is the e.m.f of the other cell?

  1. 0.4 V
  2. 4.0 V
  3. 40.0 V
  4. 0.04 V

Q28. The negative sign in calculations involving circuit problem signifies

  1. Wrong result
  2. Nothing
  3. Current is in a direction opposite to the assumed direction
  4. Use of wrong factor

Q29. Under what condition, the current drawn from the cell is maximum?

  1. R = 0
  2. R = r
  3. R > r
  4. R < r

Q30. The resistance of hot tungsten filament is about 10 times to that of cold tungsten filament. What will be the resistance of 100 W and 220 V lamp when not in use?

  1. 484 ohm
  2. 4.84 ohm
  3. 4840 ohm
  4. 48.4 ohm

Q31. Sensitivity of potentiometer can be increased by

  1. Increasing the length of potentiometer wire and reducing current.
  2. Increasing voltage
  3. Decreasing length of potentiometer wire
  4. Increasing current in circuit

Q32. When numbers of cells in series combination are increased, the current of the circuit will

  1. Decrease
  2. Increase
  3. Remain same
  4. Depends on the resistance of the circuit

Q33. The internal resistance of dry cells is ________than the common electrolytic cells.

  1. lower
  2. higher
  3. equal to
  4. lower or equal

Q34. Which statement is true about the conventional flow of current?

  1. It flows from positive to negative because protons move inside the battery from positive to the negative terminal.
  2. It flows from positive to negative terminal, because electrons move from negative to positive terminal inside a battery.
  3. It flows from negative to positive because protons move from negative to positive terminal inside the battery.
  4. It flows from negative to positive because the electrons move from negative to positive terminal inside the battery.

Q35. Meter Bridge or Slide Wire Bridge is a practical form of

  1. Potentiometer
  2. Voltmeter
  3. Ammeter
  4. Wheatstone bridge

Q36. Kirchhoff’s second law is applicable only to

  1. Open loops
  2. Closed and open loops
  3. Closed loops
  4. Mechanical systems

Q37. When number of cells in series combination is increased, the voltage of the circuit will

  1. Decrease
  2. Increase
  3. Remain same
  4. Depends on the internal resistance of the battery

Q38. In a metre bridge experiment null point is obtained at 20 cm from one end of the wire when resistance X is balanced against abother resistance Y. If X < Y, then where will be new position of the null point from the same end, if one decides to balance a resistance of 4X against Y

  1. 50 cm
  2. 80 cm
  3. 40 cm
  4. 70 cm

Q39. If the internal resistance of a cell is 20 ohm and resistance of the circuit is also 20 ohm. Will the current remain same whether the given n identical cells are in series or in parallel?

  1. Can’t predict
  2. None of the above
  3. yes
  4. No

Q40. Current provided by a battery is maximum when

  1. internal resistance is equal to external resistance
  2. internal resistance is greater then external resistance
  3. internal resistance is less than external resistance
  4. none of these

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