Why is potentiometer preferred to a voltmeter to measure the emf of cell?
A potentiometer is preferred over a voltmeter to measure the EMF of a cell because it is more accurate and can measure EMF without drawing any current from the cell.
• Equal length of silver wire an iron wire having same diameter are connected in series to a dry cell . which wire become hotter ?
The iron wire will become hotter than the silver wire.
Why give me region?
The iron wire will become hotter because it has a higher resistance than the silver wire, which means it will dissipate more energy in the form of heat.
•Draw a circuit diagram of potentiometer to measure the internal resistance of a cell. Write the formula used.
Here is the circuit diagram:
+ ----/\/\/\/\----+-----------/\/\/\/\---------- -
| | |
EMF R1 Load
| | |
- -----------------+------------------------------
The formula used to measure the internal resistance of a cell is:
r = (R1 / R2) x (E - V)
where:
r = internal resistance of the cell
R1 = resistance of the potentiometer wire
R2 = resistance of the load
E = EMF of the cell
V = potential difference measured across the potentiometer wire
•Draw a wheatstone bridge circuit and mention the balance condition for it.
Here is the circuit diagram of the Wheatstone bridge:
+----/\/\/\/\----+----/\/\/\/\----+
| | |
V1 R1 R3
| | |
\ / /
\ / /
\ / /
+----/\/\/\/\----+----/\/\/\/\----+
| | |
V2 R2 R4
| | |
---------------------------------
|
Load
|
-
The balance condition for the Wheatstone bridge is:
R1/R2 = R3/R4
When the resistances are arranged such that the ratio of R1 to R2 is equal to the ratio of R3 to R4, then the potential difference across the bridge will be zero, and the bridge is said to be balanced.
•Write down one application of potentiometer
One application of potentiometer is in volume control of audio systems, such as in radios or amplifiers. The potentiometer is used to adjust the level of the audio signal and control the volume of the output.
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