A coil of inductive reactance $31\, \Omega$ has a resistance of 8 $\Omega$. It is placed in series with a condenser of capacitative reactance $25 \,\Omega$. The combination is connected to an a.c. source of 110 V. The power factor of the circuit is :-
- 0.33
- 0.56
- 0.64
- 0.8
The Correct Option is D
Solution and Explanation
$=\frac{8}{\sqrt{8^{2}+6^{2}}}=\frac{8}{10}=0.8$
Top Questions on Power
- A body of mass \(4\) kg is placed at a point \(P\) having coordinates \( (3,4) \) m. Under the action of force \( \mathbf{F} = (2\hat{i} + 3\hat{j}) \) N, it moves to a new point \(Q\) having coordinates \( (6,10) \) m in \(4\) sec. The average power and instantaneous power at the end of \(4\) sec are in the ratio:
- Two resistors, 4Ω and 6Ω, are connected in parallel, and this combination is connected in series with a 2Ω resistor to a 12V battery. What is the total power dissipated?
- In a circuit, a current of \( 2 \, \text{A} \) flows through a resistor of resistance \( 5 \, \Omega \). Calculate the power dissipated in the resistor.
- If force is 500 N and instantaneous velocity is 20 m/s, what is the instantaneous power?
- The dimension of \( \lambda \times t \) (decay constant \(\lambda\) multiplied by time \(t\)) is:
Questions Asked in NEET exam
The current passing through the battery in the given circuit, is:
- NEET (UG) - 2025
- Current electricity
A bob of heavy mass \(m\) is suspended by a light string of length \(l\). The bob is given a horizontal velocity \(v_0\) as shown in figure. If the string gets slack at some point P making an angle \( \theta \) from the horizontal, the ratio of the speed \(v\) of the bob at point P to its initial speed \(v_0\) is :
- NEET (UG) - 2025
- Pendulums
- Two cities X and Y are connected by a regular bus service with a bus leaving in either direction every T min. A girl is driving scooty with a speed of 60 km/h in the direction X to Y. She notices that a bus goes past her every 30 minutes in the direction of her motion, and every 10 minutes in the opposite direction. Choose the correct option for the period T of the bus service and the speed (assumed constant) of the buses.
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- Relative Velocity
- The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at \(22.5^\circ\) from the polarization axis of one of the polaroids (\(I_0\) is the intensity of polarised light after passing through the first polaroid):
- NEET (UG) - 2025
- Polarization
A full wave rectifier circuit with diodes (\(D_1\)) and (\(D_2\)) is shown in the figure. If input supply voltage \(V_{in} = 220 \sin(100 \pi t)\) volt, then at \(t = 15\) msec:
- NEET (UG) - 2025
- Semiconductor Diode
Concepts Used:
Power
Power is the rate of doing an activity or work in the minimum possible time. It is the amount of energy transferred or converted per unit of time where large power means a large amount of work or energy.
For example, when a powerful car accelerates speedily, it does a large amount of work which means it exhausts large amounts of fuel in a short time.
The formula of Power:
Power is defined as the rate at which work is done upon an object. Power is a time-based quantity. Which is related to how fast a job is done. The formula for power is mentioned below.
Power = Work / time
P = W / t
Unit of Power:
As power doesn’t have any direction, it is a scalar quantity. The SI unit of power is Joules per Second (J/s), which is termed as Watt. Watt can be defined as the power needed to do one joule of work in one second.