Electric Current: Uses and Flow Conditions

JEE Main exam and NEET entrance exam aspirants must be well aware of the conditions that ensure current flow. For electric current to flow within a conductor, the following conditions must be fulfilled:

• Free Charge Carriers: Conductors must have free charge carriers, like electrons, that can freely move within the material.
• Closed Circuit: The conductor must be part of a closed circuit, providing a complete path for the current to flow.
• Potential Difference: A potential difference (voltage) must be there across the conductor. This voltage pushes the charge carriers through the conductor.

For IIT JAM exam and GATE exam students, many questions based on the EMF are important. Therefore, understanding what it means as well as its mathematical expression is important. EMF is energy per unit charge that is converted from non-electrical form (like chemical/mechanical energy) into electrical energy within a circuit. It is the force that causes current to flow. EMF is measured in volts. It is provided by sources such as batteries and generators. Mathematically, it is expressed as:

$ℰ=\frac{dW}{dq}$

Here,

• $\mathrm{ℰ }$is the electromotive force in volts
• dW is the infinitesimal amount of work done (energy) in joules (J)
• dq is the infinitesimal amount of charge flowing

Electric current has the following properties that IISER exam aspirants must be well aware of:

• Electric current flows from positive to negative direction in conventional current flow.
• The magnitude of electric current can fluctuate and it is measured in amperes.
• As per Ohm's Law, the electric current through a conductor is directly proportional to the voltage applied and it is inversely proportional to the resistance of a conductor.