Work Energy And Power

Step 1: Understanding Wattless Current
Wattless current refers to the condition when the power consumed in an AC circuit is zero. The power in an AC circuit is given by: where:
- is the power,
- is the voltage,
- is the current,
- is the phase difference between voltage and current.
Step 2: Condition for Wattless Current
- Power consumption in a circuit depends on the power factor .
- If , then: which means: - This happens when the circuit contains a pure inductor (L) or pure capacitor (C), as they store and release energy without dissipating power.
Step 3: Conclusion
- A pure inductor (L) or pure capacitor (C) does not consume power but still allows alternating current to flow.
- Since the given question specifically asks for wattless current, the correct answer is only (Inductor).

Step 1: Understanding Inductive Reactance
In an AC circuit, an inductor offers inductive reactance ( ), which is given by: where:
- is the inductive reactance (in ohms),
- is the frequency of the AC source (in Hz),
- is the inductance (in Henry).
Step 2: Given Values
- mH = H,
- Hz,
- V.
Step 3: Calculating Inductive Reactance

Step 4: Calculating RMS Current
The RMS current ( ) is given by: Thus, the rms current in the circuit is A.

Step 1: Understanding Magnetic Torque
- The torque ( ) experienced by a magnetic dipole in a uniform magnetic field is given by: where:
- is the magnetic moment of the magnet, - is the external magnetic field strength, - is the angle between the magnetic moment and the field.
Step 2: Given Values
- J, - T, - , - .
Step 3: Calculating
Rearranging the equation: Thus, the magnetic moment of the magnet is J T .