Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
An Electric Circuit is a continuous and closed path through which an electric current flows. A simple circuit consists of a cell (source), a bulb (load), a switch, and connecting wires.
Heating Effect of Current: When electric current flows through a wire, it gets hot. This is used in appliances like electric heaters, irons, and geysers. The heating element is often made of materials like Nichrome.
Magnetic Effect of Current: When an electric current passes through a wire, it produces a magnetic field around it. This turns the wire into a temporary magnet, a phenomenon discovered by Hans Christian Oersted.
An Electromagnet is a coil of insulated wire wound around a piece of magnetic material like an iron core. It behaves as a magnet only when the current is switched and loses its magnetism when the current is .
A Fuse is a safety device used in circuits. It contains a wire that melts and breaks the circuit if the current exceeds a safe limit, preventing fires and damage to appliances.
Circuit Symbols: In diagrams, a cell is represented by a long line (positive terminal, ) and a short thick line (negative terminal, ).
📐Formulae
💡Examples
Problem 1:
If a compass needle is placed near a wire and the switch is turned , why does the needle deflect?
Solution:
The needle deflects due to the Magnetic Effect of Electric Current.
Explanation:
When current flows through the wire, it creates a magnetic field around it. This magnetic field exerts a force on the compass needle, causing it to move from its original position.
Problem 2:
Why does the thin wire (filament) inside an electric bulb glow white-hot?
Solution:
It glows due to the Heating Effect of Current.
Explanation:
The filament is made of material with high resistance. When current flows through it, the electrical energy is converted into heat energy (), making it so hot that it begins to emit light.
Problem 3:
What is the difference between a magnet and an electromagnet?
Solution:
An electromagnet is a temporary magnet.
Explanation:
Unlike a permanent magnet, an electromagnet only shows magnetic properties when electric current is flowing through its coils. It can be turned or using a switch.