The resistance of the armature in the motor shown in Fig. 33-2 is 2.30 Ω. It draws a current of

step 1 Hi, for this question, want to find the back AMF when resistance of the armature is 2 .3 oms and

The resistance of the armature in the motor shown in Fig....

The resistance of the armature in the motor shown in Fig. $33-2$ is $2.30 \Omega$. It draws a current of 1.60 A when operating on 120 V . What is its back emf under these circumstances? The motor acts like a back emf in series with an IR drop through its internal resistance. Therefore, Line voltage $=$ back emf $+I r$ or Back cmf $=120 \mathrm{~V}-(1.60 \mathrm{~A})(2.30 \Omega)=116 \mathrm{~V}$

The resistance of the armature in the motor shown in Fig. $33-2$ is $2.30 \Omega$. It draws a current of 1.60 A when operating on 120 V . What is its back emf under these circumstances?

The motor acts like a back emf in series with an IR drop through its internal resistance. Therefore,
Line voltage $=$ back emf $+I r$
or
Back cmf $=120 \mathrm{~V}-(1.60 \mathrm{~A})(2.30 \Omega)=116 \mathrm{~V}$

Key Concepts

Back Electromotive Force (Back EMF)

Back EMF is the voltage generated by a motor as it rotates, which opposes the applied voltage. It arises from electromagnetic induction and acts to reduce the net voltage across the armature, thereby influencing the current drawn by the motor. This concept is fundamental in understanding the behavior of motors under load and during steady-state operation.

Armature Resistance

Armature resistance refers to the inherent electrical resistance found in the windings of the motor's armature. This resistance causes a voltage drop when current flows through the armature, and must be considered when analyzing the motor's performance, as it directly affects the net voltage available for back EMF generation.

Ohm's Law

Ohm's Law is a fundamental principle in electrical circuits that relates voltage, current, and resistance through the equation V = IR. It is instrumental in determining the voltage drop across resistive elements in a circuit, such as the armature resistance in a motor, and is essential for analyzing and designing circuits.

Kirchhoff's Voltage Law

Kirchhoff's Voltage Law states that the total sum of voltage differences around any closed loop in a circuit must equal zero. This law is used to relate the applied voltage to the sum of voltage drops across components like resistors and the induced back EMF in motors, ensuring the conservation of energy within the circuit.

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