Wire Wound Variable Resistor RHEOSTAT || 2nd Year || Physics || KPK & Federal Board

Summary

Key Points

• A variable resistor is a resistor whose resistance value can be changed according to the user's needs. 0:02
• The fundamental principle behind variable resistors is that the resistance of a wire is directly proportional to its length. 3:44
• A wire-wound variable resistor is constructed by winding a resistive wire onto an insulating cylinder, allowing for a longer wire length in a compact space. 7:58
• The rheostat has a sliding terminal that moves along the resistive wire, changing the effective length of the wire through which current flows. 11:43
• By adjusting the sliding terminal, the resistance in the circuit can be increased or decreased, thereby controlling the amount of current flowing. 15:25
• Wire-wound resistors are typically made from alloys like constantan, nichrome, or manganin, which have high resistivity. 19:20
• Rheostats can be connected in a circuit to regulate the flow of charge, effectively controlling the current. 23:34
• Beyond current control, a rheostat can also function as a voltage divider, allowing for a variable potential difference to be applied across a load. 27:38
• When used as a voltage divider, the rheostat is connected across a voltage source, and the output voltage is taken between one end of the resistive wire and the sliding contact. 31:55
• The voltage division equation shows that the output voltage is proportional to the ratio of the resistance between the sliding contact and one end, to the total resistance of the wire. 35:56