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A component used in electric circuits to vary the current by changing the resistance without changing the voltage source is called a ___________.
Rheostat
Galvanometer
Ammeter
Capacitor
Rheostat
A rheostat is a variable resistor used in circuits to regulate current flow. By adjusting its sliding contact, the effective length of the resistive path changes, thereby altering the total resistance of the circuit without requiring a change in the voltage source.
A rheostat is a variable resistor used in circuits to regulate current flow. By adjusting its sliding contact, the effective length of the resistive path changes, thereby altering the total resistance of the circuit without requiring a change in the voltage source.
Think of a rheostat like a water faucet. Just as turning the handle restricts the pipe opening to control water flow without changing the water pressure from the tank, the rheostat restricts electron flow to control current without changing the voltage source.
V=I├ЧR тАФ Ohm's Law representing the relationship between Voltage, Current, and Resistance.
R=╧БALтАЛ тАФ Formula for resistance where L is length, A is area, and ╧Б is resistivity.
The rheostat operates based on Ohm's Law, V=I├ЧR. When the slider moves, it changes the length of the resistive wire through which the current flows. Since resistance R is directly proportional to length L (given by R=╧БALтАЛ), changing L effectively modulates R, which in turn adjusts the current I while the potential difference V remains constant.
Rheostats are often used as current limiters in laboratory experiments.
A potentiometer is a specific type of variable resistor connected as a potential divider.
The SI unit of resistance is the Ohm (╬й).
Allows smooth, continuous control of current.
Versatile for testing components at different operating points.
Can dissipate significant energy as heat during operation.
Physical size can be large for high-power applications.
Dimming lights (incandescent bulbs).
Controlling the speed of DC motors.
Galvanometer: Instrument for detecting small electric currents.
Ammeter: Instrument for measuring the magnitude of current in a circuit.
Capacitor: Device used to store electrical energy in an electric field.
A is correct тАФ A rheostat is specifically designed as a variable resistor to modulate circuit current.
In competitive exams, remember that an ammeter is always connected in series, while a voltmeter is connected in parallel; a rheostat is used as a series component to adjust circuit-wide current.