Law of Combination of Resistances Using Metre Bridge – Viva Questions
Law of Combination of Resistances Using Metre Bridge – Viva Questions
This post presents a carefully structured set of viva questions on the law of combination of resistances using a metre bridge. It helps students prepare confidently for CBSE physics practical viva voce by covering both series and parallel combinations in a clear, examiner-oriented manner.
Basic Viva Questions
Q1. What is meant by combination of resistances?
Combination of resistances refers to connecting two or more resistors together to obtain an equivalent resistance.
Q2. What are the two types of combination of resistances?
Resistances can be combined in series and in parallel.
Q3. What is a metre bridge?
A metre bridge is a practical form of Wheatstone bridge used to compare and measure resistances.
Q4. Which principle does the metre bridge work on?
It works on the principle of Wheatstone bridge.
Q5. Why is this experiment performed using a metre bridge?
Because a metre bridge allows accurate comparison of equivalent resistances.
Procedure-Related Viva Questions
Q6. How are resistances connected for series combination in this experiment?
First, individual resistances are measured. Then, the resistors are connected end-to-end in one gap of the metre bridge.
Q7. How are resistances connected for parallel combination?
Both resistors are connected across the same two points to form a parallel combination.
Q8. Why are individual resistances measured before combination?
Because the measured values are required for comparison with the equivalent resistance.
Q9. Why should the jockey be touched gently on the wire?
Gentle contact prevents change in wire resistance and avoids contact resistance errors.
Q10. Why should the balancing point not be very close to the ends?
Because end resistances introduce significant experimental error.
Conceptual Viva Questions
Q11. State the law of series combination of resistances.
In series combination, the equivalent resistance equals the sum of individual resistances.
Q12. State the law of parallel combination of resistances.
In parallel combination, the reciprocal of equivalent resistance equals the sum of reciprocals of individual resistances.
Q13. Why is equivalent resistance higher in series combination?
Because current must pass through each resistor sequentially.
Q14. Why is equivalent resistance lower in parallel combination?
Because multiple current paths are available for charge flow.
Q15. What quantity remains same in series and parallel circuits?
Current remains same in series, whereas potential difference remains same in parallel.
Application-Based Viva Questions
Q16. Where is series combination used in daily life?
Series combination is used where current control is required, such as in fuse connections.
Q17. Where is parallel combination commonly used?
Parallel combination is used in household wiring so that appliances work independently.
Q18. Why is household wiring not done in series?
Because failure of one appliance would stop current through all others.
Q19. Why is verification of these laws important?
Because it confirms theoretical laws through experimental observation.
Q20. Can this experiment be performed without a metre bridge?
Yes, but the metre bridge provides higher accuracy and reliability.
Error Analysis Viva Questions
Q21. What types of errors occur in this experiment?
Systematic errors, random errors, and observational errors occur.
Q22. What is systematic error in this experiment?
Systematic error arises due to end resistance of copper strips and non-uniform wire.
Q23. What are random errors?
Random errors occur due to slight variations in jockey position and galvanometer sensitivity.
Q24. What are observational errors?
Observational errors occur due to parallax while reading the balancing length.
Q25. How can experimental errors be minimized?
Errors can be minimized by taking mean readings, keeping contacts clean, and avoiding heating.
Quick Examiner-Style Viva Questions
- SI unit of resistance: Ohm (Ω)
- Series combination formula: R = R₁ + R₂
- Parallel combination formula: 1/R = 1/R₁ + 1/R₂
- Null point indicates: Balanced Wheatstone bridge
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