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Chapter 14: Problem 2090

The power factor of a good choke coil is (a) Nearly zero (b) Exactly zero (c) Nearly one (d) Exactly one

Short Answer

Expert verified
The power factor of a good choke coil is (a) nearly zero, as it has very large inductive reactance (XL) compared to its resistance (R), making the ratio \(PF = \frac{R}{X_L}\) very small or close to zero.

Step by step solution

01

Analyze the given formula

Recall the power factor formula: \(PF = \frac{R}{\sqrt{R^2 + X_L^2}}\) As a good choke coil has very large inductive reactance (XL) compared to its resistance (R), we can deduce that: \(X_L >> R\) Now, let's analyze the power factor formula with this condition.
02

Apply the condition and evaluate the formula

Since \(X_L >> R\), we can consider \(R^2 + X_L^2 \approx X_L^2\). So, the power factor formula becomes: \(PF = \frac{R}{\sqrt{X_L^2}}\) We notice that the denominator now becomes an absolute inductive reactance value, which is significantly larger than resistance.
03

Compare the numerator and denominator

Now, we can simplify the formula: \(PF = \frac{R}{X_L}\) Given that the inductive reactance of a good choke coil (XL) is very large compared to its resistance (R), we can deduce that the ratio of R to XL will be very small or close to zero.
04

Choose the correct option

Since the power factor is very small or close to zero, the correct answer is (a) nearly zero.

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Most popular questions from this chapter

A choke coil has (a) High inductance and low resistance (b) Low inductance and high resistance (c) High inductance and high resistance (d) Low inductance and low resistance

A coil of inductive reactance \(31 \Omega\) has a resistance of \(8 \Omega\). It is placed in series with a condenser of capacitive reactance \(25 \Omega\). The combination is connected to an a.c. source of 110 volt. The power factor of the circuit is. (a) \(0.80\) (b) \(0.33\) (c) \(0.56\) (d) \(0.64\)

Same current is flowing in two alternating circuits. The first circuits contains only inductance and the other contains only a capacitor. If the frequency of the emf of ac is increased the effect on the value of the current will be. (a) Increase in the first circuit and decrease in other (b) Increase in both the circuit (c) Decrease in both the circuit (d) Decrease in the first and increase in other

The core of a transformer is laminated so that...... (a) Ratio of I/ \(p\) \& O/p voltage increases (b) Rusting of core may be stopped (c) Energy loss due to eddy current may be reduced (d) Change in flux is increased

In general in an alternating current circuit. (a) The average value of current is zero. (b) The average value of square of current is zero. (c) Average power dissipation is zero. (d) The phase difference between voltage and current is zero.
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