The correct answer is A. Kelvin’s law.
Kelvin’s law states that the total annual cost of a conductor is minimum when the variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors.
Ohm’s law states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to the resistance of the conductor.
Kirchhoff’s law states that the sum of the currents entering a node is equal to the sum of the currents leaving the node.
Faraday’s law states that the induced electromotive force in a circuit is equal to the rate of change of magnetic flux through the circuit.
Here is a more detailed explanation of each option:
- Kelvin’s law states that the total annual cost of a conductor is minimum when the variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors. This means that the cost of the conductor should be balanced with the cost of the energy that is wasted in the conductor.
- Ohm’s law states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to the resistance of the conductor. This means that the current through a conductor will increase if the voltage across it increases or if the resistance of the conductor decreases.
- Kirchhoff’s law states that the sum of the currents entering a node is equal to the sum of the currents leaving the node. This means that the total current entering a node must equal the total current leaving the node.
- Faraday’s law states that the induced electromotive force in a circuit is equal to the rate of change of magnetic flux through the circuit. This means that the electromotive force (EMF) induced in a circuit is proportional to the rate of change of the magnetic flux through the circuit.