Electrical Power

We need to determine the cause of rotation of the shiny metal disk in an analog electric power meter.
Step 1: Identify the working principle.
An analog electric power meter uses an aluminum disk that rotates due to the interaction of magnetic fields from two coils (voltage and current coils).
Step 2: Determine the cause of rotation.
The magnetic fields induce eddy currents in the disk. These eddy currents interact with the fields, producing a torque that causes rotation.
Final Answer:

We need to find the current through a pure inductor with an AC voltage applied.
Step 1: Write the voltage equation. Step 2: Relate voltage to current. For an inductor: Step 3: Integrate to find the current. Final Answer:

The power dissipated by the bulb is given by: where and . The resistance of the bulb can be found using Ohm's law: Now, the total resistance in the circuit is . Using the formula for the emf: Substituting the values, we find that the emf is 2.67 V.