Question

▶️describe the principle and construction of a potentiometer why do we prefer a potentiometer with longer?

Answer 1

Answer:

Construction and Working Principle

The potentiometer consists of a long resistive wire L made up of magnum or with constantan and a battery of known EMF V. This voltage is called as driver cell voltage. Connect the two ends of the resistive wire L to the battery terminals as shown below; let us assume this is a primary circuit arrangement. One terminal of another cell (whose EMF E is to be measured) is at one end of the primary circuit and another end of the cell terminal is connected to any point on the resistive wire through a galvanometer G. Now let us assume this arrangement is a secondary circuit. The arrangement of the potentiometer as shown in attachment.

Construction of Potentiometer

The basic working principle of this is based on the fact that the fall of the potential across any portion of the wire is directly proportional to the length of the wire, provided wire has uniform cross-sectional area and the constant current flowing through it.“When there is no potential difference between any two nodes there is electric current will flow”.

Now the potentiometer wire is actually a wire with high resistivity (ῥ) with uniform cross-sectional area A. Thus, throughout the wire, it has uniform resistance. Now this potentiometer terminal connected to the cell of high EMF V (neglecting its internal resistance) called driver cell or the voltage source. Let the current through the potentiometer is I and R is the total resistance of the potentiometer.

Answer 2

❤EʟʟᴏᴏᴏO❤

Wᴇ ᴘʀᴇғᴇʀ ᴀ ᴘᴏᴛᴇɴᴛɪᴏᴍᴇᴛᴇʀ ᴏғ ʟᴏɴɢᴇʀᴡɪʀᴇ sɪᴍᴘʟʏ ʙᴇᴄᴀᴜsᴇ ᴛʜᴇ ᴠᴏʟᴛᴀɢᴇ ᴘᴇʀ ᴜɴɪᴛ ʟᴇɴɢᴛʜ ᴅʀᴏᴘs ᴀs ᴛʜᴇ ʟᴇɴɢᴛʜ ɪɴᴄʀᴇᴀsᴇs ᴀɴᴅ ʜᴇɴᴄᴇ ᴡᴇ ɢᴇᴛ ᴍᴏʀᴇ ᴀᴄᴄᴜʀᴀᴄʏ ᴛʜᴀɴ ʙᴇғᴏʀᴇ. Aɴᴏᴛʜᴇʀ ɪs ᴛʜᴀᴛ ᴀ ʟᴏɴɢᴇʀ ᴡɪʀᴇ ʜᴀs ᴍᴏʀᴇ ᴀʀᴇᴀ ғᴏʀ ᴘɪᴄᴋɪɴɢ ᴏғғ ᴀ ᴠᴏʟᴛᴀɢᴇ ᴠɪᴀ ᴛʜᴇ ᴡɪᴘᴇʀ ᴄᴏɴᴛᴀᴄᴛ, ᴛʜᴜs ᴀ ᴍᴜᴄʜ ғɪɴᴇʀ ᴄᴏɴᴛʀᴏʟ ᴏғ ᴛʜᴇ ᴏᴜᴛᴘᴜᴛ ᴠᴏʟᴛᴀɢᴇ ɪs ᴘᴏssɪʙʟᴇ .

Pʀɪɴᴄɪᴘʟᴇ⏬

Tʜᴇ ᴘʀɪɴᴄɪᴘʟᴇ ᴏғ ᴛʜᴇ ᴘᴏᴛᴇɴᴛɪᴏᴍᴇᴛᴇʀ ɪs ᴛʜᴀᴛ: Fᴏʀ ᴀ ᴡɪʀᴇ ʜᴀᴠɪɴɢ ᴜɴɪғᴏʀᴍ ᴀʀᴇᴀ ᴏғ ᴄʀᴏss sᴇᴄᴛɪᴏɴ ᴀɴᴅ ᴜɴɪғᴏʀᴍ ᴄᴏᴍᴘᴏsɪᴛɪᴏɴ,ᴛʜᴇ ᴘᴏᴛᴇɴᴛɪᴀʟ ᴅʀᴏᴘ ɪs ᴅɪʀᴇᴄᴛʟʏ ᴘʀᴏᴘᴏʀᴛɪᴏɴᴀʟ ᴛᴏ ᴛʜᴇ ʟᴇɴɢᴛʜ ᴏғ ᴡɪʀᴇ. Tʜᴇ ᴀʙᴏᴠᴇ ᴘʀɪɴᴄɪᴘʟᴇ ɪs ᴠᴀʟɪᴅ ᴡʜᴇɴᴘᴏᴛᴇɴᴛɪᴏᴍᴇᴛᴇʀ ɪs ᴜsᴇᴅ ɪɴ ᴄᴏᴍᴘᴀʀɪɴɢ ᴛʜᴇ EMF ᴏғ ᴛᴡᴏ ᴄᴇʟʟs .