Question: Q. 5. (i) State the working principle of a potentiometer. With the help of the circuit diagram, explain how a potentiometer is used to compare the emf’s of two primary cells. Obtain the required expression used for comparing the emfs.
(ii) Write two possible causes for one sided deflection in a potentiometer experiment.
R [Delhi I, II, III 2013]
Show Answer
Solution:
Ans. (i) Principle : Try yourself Similar to Q. 2 Short Answer Type Questions-II
(ii) (a) When the driver cell / source cell has emf less than the emf of the cells to be compared.
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(b) When the positive end of the potentiometer wire is connected to negative terminal of the cell whose emf is to be compared / determined.
[CBSE Marking Scheme 2013] 1
(AI Q. 6. (i) Draw a circuit diagram of a metre bridge used to determine the unknown resistance
(ii) What does the term ’end error’ in a metre bridge circuit mean and how is it corrected? How will the balancing point be affected, if the positions of the battery and galvanometer are interchanged in a metre bridge experiment? Give reason for your answer. R [Delhi Compt I, II, III 2017]
Ans. (i) Labelled circuit diagram of metre bridge & derivation of expression of
[CBSE Marking Scheme 2017]
Detailed Answer :
(i) Try yourself Similar to Q. 9, Short Answer Type Questions-II.
(ii) The error which arises on account of resistance of copper strips and the connecting wire at both ends of the metre bridge is called end error.
It is minimized by adjusting the balance point near the middle point of the bridge.
No effect, as the bridge remains balanced.
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UNIT - III
