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In an electric circuit, the device that acts as a variable resistor is called ________.
galvanometer
ammeter
voltmeter
rheostat
rheostat
A rheostat is an adjustable resistor used in electrical circuits to vary the resistance without interrupting the flow of current. It allows for the continuous control of electric current in a circuit, which is essential for regulating devices like dimmers or motor speed controllers.
A rheostat is an adjustable resistor used in electrical circuits to vary the resistance without interrupting the flow of current. It allows for the continuous control of electric current in a circuit, which is essential for regulating devices like dimmers or motor speed controllers.
Think of a rheostat like a water faucet; just as turning the handle restricts or allows the flow of water through a pipe, the rheostat restricts or allows the flow of electrons through a circuit.
R=╧БAlтАЛ тАФ where R is resistance, ╧Б is resistivity, l is length, and A is cross-sectional area
I=RVтАЛ тАФ Ohm's Law, relating current, voltage, and resistance
A rheostat operates by changing the length of the resistive path through which the current flows. According to Ohm's Law, as resistance R increases while voltage V remains constant, the current I decreases, as defined by I=RVтАЛ. By moving a sliding contact along a resistive wire or coil, the effective length of the resistor is altered, thereby modifying the total resistance in the circuit.
A rheostat is also known as a variable resistor.
It is connected in series with the load to limit the current.
The SI unit of resistance is the Ohm (╬й).
Allows smooth and continuous variation of current
Simple construction
Consumes energy in the form of heat
Less efficient compared to modern power electronic controllers
Dimming lights
Controlling the speed of DC motors
Galvanometer: Detects small electric currents.
Ammeter: Measures the magnitude of electric current.
Voltmeter: Measures the potential difference (voltage) between two points.
D is correct тАФ The rheostat is the specific device designed to function as a variable resistor to control current levels in a circuit.
Remember that an ammeter is connected in series to measure current, while a voltmeter is connected in parallel to measure potential difference; a rheostat is also connected in series to control current.
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