NEET UG - Kirchhoffs laws and applications, Wheatstone bridge, metre bridge Online Test (MCQ Quiz)

1. Kirchhoff's first law (junction rule) is a consequence of which fundamental law?

A) Conservation of Energy B) Conservation of Momentum C) Conservation of Charge D) Conservation of Mass

2. Kirchhoff's second law (loop rule) is a consequence of which fundamental law?

A) Conservation of Charge B) Conservation of Mass C) Conservation of Momentum D) Conservation of Energy

3. According to Kirchhoff's first law, the algebraic sum of currents entering a junction is equal to:

A) The algebraic sum of currents leaving the junction B) Zero C) The total resistance at the junction D) The total voltage at the junction

4. In Kirchhoff's second law, the algebraic sum of potential differences (voltage drops and rises) around any closed loop in a circuit is:

A) Always positive B) Always negative C) Equal to the net emf of the loop D) Zero

5. Which of the following statements best describes Kirchhoff's second law?

A) The sum of currents entering a junction equals the sum of currents leaving it. B) The sum of voltages around a closed loop is zero. C) The product of voltage and current is constant. D) The resistance is directly proportional to length and inversely proportional to area.

6. A Wheatstone bridge is used to measure:

A) Unknown voltage B) Unknown resistance C) Unknown current D) Unknown capacitance

7. For a Wheatstone bridge to be balanced, the ratio of resistances in the two arms must be:

A) Equal B) Reciprocal C) Proportional to the galvanometer current D) Inversely proportional to the galvanometer current

8. In a balanced Wheatstone bridge, the current through the galvanometer is:

A) Maximum B) Minimum but non-zero C) Zero D) Equal to the current in the other arms

9. The condition for a Wheatstone bridge to be balanced is P/Q = R/S, where P, Q, R, and S are resistances. If P=2Ω, Q=4Ω, and R=6Ω, what is the value of S for balance?

A) 3Ω B) 8Ω C) 12Ω D) 24Ω

10. A metre bridge is a practical application of which principle?

A) Kirchhoff's laws B) Ohm's law C) Wheatstone bridge D) Faraday's law of induction

11. In a metre bridge experiment, the unknown resistance is placed in:

A) The left gap B) The right gap C) Series with the galvanometer D) Parallel to the battery

12. The jockey in a metre bridge is used to:

A) Adjust the battery voltage B) Measure the resistance C) Find the null point on the wire D) Connect the galvanometer

13. If the balancing length for an unknown resistance 'X' in a metre bridge is 'l', and the total length of the wire is 100 cm, the resistance of the wire per unit length is assumed to be uniform. The formula to calculate X is:

A) X = R * (l / (100 - l)) B) X = R * ((100 - l) / l) C) X = R * (l / 100) D) X = R * (100 / l)

14. A metre bridge is most accurate when the unknown resistance is:

A) Very low B) Very high C) Of the order of the resistance of the bridge wire D) Zero

15. Which of the following is a disadvantage of using a metre bridge?

A) It requires a galvanometer B) It depends on Ohm's law C) It has limited accuracy due to the resistance of the end connections D) It can measure very low resistances accurately

16. Consider a circuit with three resistors R1, R2, and R3 connected in series to a battery. According to Kirchhoff's second law, the sum of voltage drops across R1, R2, and R3 will be equal to:

A) Zero B) The voltage drop across R1 only C) The total emf of the battery D) The sum of currents through the resistors

17. In a parallel circuit with branches having resistors R1, R2, and R3, Kirchhoff's first law applied at a junction states that the total current entering the junction is equal to:

A) The sum of voltages across R1, R2, and R3 B) The sum of currents flowing through R1, R2, and R3 C) The difference between currents in R1 and R2 D) Zero

18. When applying Kirchhoff's second law, if we traverse a loop in the direction of the current through a resistor, the potential difference is taken as:

A) Positive B) Negative C) Zero D) Dependent on the resistance value

19. When applying Kirchhoff's second law, if we traverse a loop in the opposite direction of the current through a resistor, the potential difference is taken as:

A) Negative B) Zero C) Positive D) Dependent on the battery voltage

20. If we traverse a loop in the direction of the emf source (from negative to positive terminal) while applying Kirchhoff's second law, the emf is taken as:

A) Negative B) Zero C) Positive D) Dependent on the circuit current

21. If we traverse a loop in the opposite direction of the emf source (from positive to negative terminal) while applying Kirchhoff's second law, the emf is taken as:

A) Positive B) Zero C) Negative D) Dependent on the resistance

22. A Wheatstone bridge circuit has four resistors P, Q, R, and S, and a galvanometer G. If the bridge is balanced, which of the following is true?

A) P = Q = R = S B) P/Q = S/R C) P/R = Q/S D) P*S = Q*R

23. In a Wheatstone bridge, if the galvanometer shows deflection, it means the bridge is:

A) Balanced B) Unbalanced C) Overloaded D) Short-circuited

24. The sensitivity of a Wheatstone bridge is highest when:

A) All resistances are very low B) All resistances are very high C) The resistances are comparable D) One resistance is zero

25. The metre bridge works on the principle of the Wheatstone bridge and is used to determine an unknown resistance by comparing it with:

A) A standard known resistance B) The resistance of the bridge wire C) The resistance of the galvanometer D) The battery voltage

26. In a metre bridge experiment, if the jockey is at the 40 cm mark from the left end and the galvanometer shows no deflection, and the known resistance in the right gap is 10Ω, what is the unknown resistance in the left gap?

A) 6Ω B) 15Ω C) 6.67Ω D) 25Ω

27. If in the metre bridge experiment, the balancing length is found to be very small (e.g., 5 cm), it implies that the unknown resistance is:

A) Much larger than the known resistance B) Much smaller than the known resistance C) Equal to the known resistance D) Zero

28. Which component is crucial for detecting the null point in both Wheatstone bridge and metre bridge?

A) Ammeter B) Voltmeter C) Galvanometer D) Ohmmeter

29. Kirchhoff's junction rule is applicable to:

A) Any point in a circuit B) Only closed loops C) Only junctions where currents meet D) Only series circuits

30. Kirchhoff's loop rule is applicable to:

A) Any two points in a circuit B) Only junctions C) Any closed electrical path (loop) D) Only parallel circuits

31. A complex circuit can be simplified and analyzed using:

A) Ohm's Law alone B) Kirchhoff's laws C) A single resistor formula D) Direct measurement with a multimeter

32. In a Wheatstone bridge, if P=3Ω, Q=6Ω, R=4Ω, and S=8Ω, what is the ratio P/Q and R/S?

A) 0.5 and 0.5 B) 2 and 2 C) 0.5 and 2 D) 2 and 0.5

33. What happens to the current through the galvanometer in a Wheatstone bridge if the battery voltage is increased?

A) It decreases B) It remains the same (if balanced) C) It increases (if unbalanced) D) It becomes zero

34. The resistance wire used in a metre bridge is typically made of:

A) Copper B) Aluminium C) Manganin or Nichrome D) Silver

35. Why is a galvanometer used instead of an ammeter in a Wheatstone bridge to detect balance?

A) Ammeters measure current, galvanometers detect very small currents. B) Ammeters are too expensive. C) Galvanometers measure voltage. D) Ammeters are not sensitive enough to detect zero current.

36. If the unknown resistance in a metre bridge is very low, the balancing length 'l' will be:

A) Close to 100 cm B) Close to 0 cm C) Close to 50 cm D) Irrelevant

37. If the unknown resistance in a metre bridge is very high, the balancing length 'l' will be:

A) Close to 0 cm B) Close to 50 cm C) Close to 100 cm D) Zero

38. The end resistances of the metre bridge connections can be minimized by:

A) Using thick connecting wires B) Using loose connections C) Ensuring all connections are tight and clean, and using a four-way key D) Increasing the length of the bridge wire

39. In applying Kirchhoff's laws, the choice of direction for current in a loop is:

A) Arbitrary; the final result will be correct regardless B) Fixed and must follow convention C) Dependent on the battery polarity D) Dependent on the resistance values

40. Consider a junction with three incoming currents I1, I2, I3 and two outgoing currents I4, I5. Kirchhoff's first law states:

A) I1 + I2 + I3 = I4 + I5 B) I1 + I2 = I3 + I4 + I5 C) I1 = I2 = I3 = I4 = I5 D) I1 + I2 + I3 + I4 + I5 = 0

41. A galvanometer deflects to the right when current flows in a certain direction. If the galvanometer in a Wheatstone bridge deflects to the right when the jockey is moved towards the right end of the wire, what does this indicate about the potential?

A) Potential at the right end is higher than the left end. B) Potential at the left end is higher than the right end. C) Potential is equal at both ends. D) Current is zero.

42. In a metre bridge, if the known resistance is R and the balancing length is l, the unknown resistance X is given by X = R * (l / (100 - l)). If R = 50Ω and l = 60 cm, what is X?

A) 75Ω B) 30Ω C) 50Ω D) 100Ω

43. Which of the following is NOT a condition for applying Kirchhoff's laws?

A) The circuit must consist of linear circuit elements. B) The circuit must be a DC circuit. C) The circuit must contain at least one closed loop. D) The circuit must contain junctions where currents split or merge.

44. A galvanometer with resistance G is connected in series with a Wheatstone bridge. If the bridge is balanced, the current through G is zero. What happens if G is increased?

A) The balance condition changes. B) The bridge becomes more sensitive. C) The current through G increases. D) The balance point shifts.

45. The metre bridge is preferred over the Wheatstone bridge for measuring moderate resistances because:

A) It is more accurate for high resistances. B) It is simpler to construct and use for moderate values. C) It does not require a galvanometer. D) It can measure very low resistances accurately.

46. If the jockey is moved along the wire in a metre bridge, the resistance of the wire segment changes. This change in resistance causes a change in:

A) The total current from the battery B) The potential difference across the unknown resistance C) The potential difference across the galvanometer D) The balancing length

47. In a Wheatstone bridge, if the resistance of one arm is increased significantly, what is the likely effect on the balance condition?

A) The bridge will become balanced. B) The balance point will shift. C) The galvanometer current will become zero. D) The battery voltage will need to be adjusted.

48. The formula P/Q = R/S for a balanced Wheatstone bridge assumes:

A) The galvanometer has infinite resistance. B) The galvanometer has zero resistance. C) The galvanometer has a finite, non-zero resistance. D) The battery has zero internal resistance.

49. Which law is fundamentally applied when analyzing the potential drop across resistors in a closed loop according to Kirchhoff's second law?

A) Ampere's Law B) Faraday's Law C) Gauss's Law D) Conservation of Energy

Kirchhoffs laws and applications, Wheatstone bridge, metre bridge - Online Test

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