What is null point in galvanometer?
Null point in the galvanometer is obtained when a cell of emf E and internal resisance r is connncted across the length of 22 cm wire of the potentiometer . Now a resistane of 10Ω is connected across the terminals of the cell (by closing the key K) and null point is obtained against the length of cm.
When a balance point is obtained in a potentiometer a current is drawn from?
When a balance point is obtained in a potentiometer for finding the internal resistance of a cell, the current through the potentiometer wire is due to. the cell whose internal resistance is to be found. the auxiliary battery. both cell and auxiliary battery.
Why potentiometer is preferred over voltmeter?
The potentiometer is preferred over voltmeter for measurement of emf of cell because the potentiometer does not draw any current for itself from the primary circuit. Therefore it gives more accurate measurement thereby acting as an ideal voltmeter.
Why copper is not used in potentiometer?
Copper has low resistivity and a high temperature coefficient of resistance and hence we do not use it in potentiometer.
What are the disadvantages of potentiometer?
Disadvantages of PotentiometerThe use of Potentiometer is inconvenient.The area of cross-Section of potentiometer wire must be uniform which is practically not possible.During experiment the temperature of potentiometer wire must remain uniform. The major disadvantage is that it requires a large force to move their sliding contacts i.e. wiper.
Why manganin wire is used in potentiometer?
Manganin foil and wire is used in the manufacture of POTENTIOMETER because of its virtually zero temperature coefficient of resistance value and long term stability. Also it has a positive temperature coefficient of resistance. Temperature coefficients can be controlled by simple heat treatment.
Which wire is used for potentiometer?
Which wire is thicker copper or manganin?
Answer: Mangnese wire should be thicker to compensate for it’s higher resistivity . Answer: Since the latter two metals have resistivity greater than copper, the pure copper has lower resistivity and the manganin thus has to be thicker to have the same resistance.
Why are metal strips used in Metre bridge?
The metallic strips in the meter bridge needs to be of a very good conductor, hence mostly they are made up of copper metal. If the metallic strips are not very good conductors then their resistance will also be a matter of concern and may affect measurements .
Why are the connectors in a Metre bridge made of thick copper strips?
(a) The resistivity of a copper wire of very low. Also, the connections are thick, so that the area is quite large and hence the resistance of the wire is almost negligible. (b) It is preffered to obtain the balance point in the middle of the meter bridge wire because it improves the sensitivity of the meter bridge.
What is the best material used for making connecting wires?
Expert Answer:’Copper or Aluminium’ is used as a material for making connection wires because the resistivity of these materials is very small and thus wires made of these materials possess negligible resistance.The connection wires are made thick so that their resistance can be considered as negligible.