Top 20 Viva Questions for Physics Practical: Half-Deflection Method for Galvanometer Resistance & Figure of Merit
Preparing for your Physics practical viva on the experiment “To determine the resistance of a galvanometer by half-deflection method and to find the figure of merit”? Here's a list of the top 20 most expected viva questions with clear and concise answers, along with brief explanations. This guide will help you ace your practical viva confidently!
Q1. What is a galvanometer?
Answer: A galvanometer is an instrument used to detect small electric currents.Explanation: It shows deflection when a current passes through it, indicating the presence and direction of current in a circuit.
Q2. What is the figure of merit of a galvanometer?
Answer: It is the current required to produce unit deflection in the galvanometer.Explanation: Usually expressed in µA/division, it tells how sensitive the galvanometer is.
Q3. What is the working principle of a galvanometer?
Answer: It works on the principle that a current-carrying coil placed in a magnetic field experiences a torque. Explanation: This torque causes the coil (and the pointer) to deflect, showing the presence of current.
Q4. What is meant by half-deflection method?
Answer: It is a method to calculate the resistance of a galvanometer by reducing its deflection to half.Explanation: A known resistance is connected in parallel to bring the deflection to half, enabling the calculation of galvanometer resistance.
Answer: To simplify the calculation of galvanometer resistance.
Q5. Why is the deflection reduced to half in this method?
Answer: To simplify the calculation of galvanometer resistance. Explanation: At half-deflection, the shunt resistance equals the galvanometer resistance, making the math straightforward.
Q6. How is galvanometer resistance calculated in this method?
Answer: It equals the resistance connected in parallel at half deflection.Explanation: This works because the current gets equally divided between the galvanometer and the parallel resistance.
Answer: K = V / (n × G)
Q7. What formula is used to find the figure of merit?
Answer: K = V / (n × G)Explanation: Here, V = voltage across galvanometer, n = deflection in divisions, G = galvanometer resistance.
Answer: Avoid tapping the galvanometer, handle with care, take readings at eye level.
Explanation: These prevent mechanical damage and ensure accurate deflection readings.
Answer: It divides the current, reducing deflection.
Q8. What precautions should be taken during this experiment?
Answer: Avoid tapping the galvanometer, handle with care, take readings at eye level.Explanation: These prevent mechanical damage and ensure accurate deflection readings.
Q9. What is the function of the shunt resistance?
Answer: It divides the current, reducing deflection.Explanation: This helps in achieving half deflection and calculating galvanometer resistance.
Answer: To limit the current and protect the galvanometer.
Q10. Why do we use a high resistance in series with the battery?
Answer: To limit the current and protect the galvanometer.Explanation: Excessive current can damage the delicate coil inside the galvanometer.
Answer: A moving coil galvanometer.
Explanation: It is sensitive and commonly used in lab setups for current detection.
Answer: The smallest deflection it can measure.
Q11. What kind of galvanometer is used in the lab?
Answer: A moving coil galvanometer.Explanation: It is sensitive and commonly used in lab setups for current detection.
Q12. What is the least count of a galvanometer?
Answer: The smallest deflection it can measure.Explanation: It depends on the scale divisions and sensitivity of the device.
Answer: It prevents oscillations and brings the needle to rest quickly.
Q13. What is meant by critical damping in a galvanometer?
Answer: It prevents oscillations and brings the needle to rest quickly.Explanation: Useful for getting accurate, stable readings.
Answer: To detect both direction and magnitude of current.
Q14. Why is the zero of the galvanometer in the center?
Answer: To detect both direction and magnitude of current.Explanation: It shows positive and negative deflections for current in both directions.
Answer: It may get damaged due to excess current.
Q15. What happens if the galvanometer is used without protection?
Answer: It may get damaged due to excess current.Explanation: Galvanometers are delicate and should always be used with protective resistors.
Answer: No, only very small currents.
Explanation: For larger currents, a shunt is used and it becomes an ammeter.
Answer: Microampere per division (µA/div).
Explanation: It tells how many microamperes produce one scale division deflection.
Answer: To control the current in the circuit.
Q16. Can the galvanometer be used to measure current directly?
Answer: No, only very small currents.Explanation: For larger currents, a shunt is used and it becomes an ammeter.
Q17. What is the unit of the figure of merit?
Answer: Microampere per division (µA/div).Explanation: It tells how many microamperes produce one scale division deflection.
Q18. What is the role of rheostat in this experiment?
Answer: To control the current in the circuit.Explanation: Helps adjust current to get full and half deflections safely.
Q19. What type of graph can be plotted in this experiment?
Answer: A deflection vs resistance graph (optional).Explanation: Helps visualize how current and deflection relate to resistance.
Answer: It may affect resistance and sensitivity.
Q20. How does temperature affect the galvanometer readings?
Answer: It may affect resistance and sensitivity.Explanation: Warming can increase resistance in the coil, altering deflection slightly.
Conclusion
Understanding these viva questions and their answers will give you the confidence to perform well in your Physics practical. The half-deflection method is a brilliant and simple way to determine galvanometer resistance and its figure of merit. Don’t forget to handle the galvanometer carefully and take readings patiently for the best results!
Good luck and happy experimenting! 👍
No comments:
Post a Comment