ELECTRIC CURRENT AND ITS EFFECTS | SPEED NOTES | SCIENCE | CBSE | CLASS 7

Chapter – 14 Electric Current andits Effects

Electric Current: Flow of electrons through a conductor. It is convenient to represent electric components by symbols. Using these, an electric circuit can be represented by a circuit diagram. When anelectric current flows through a wire, the wire getsheated. It isthe heating effect of current. Thiseffect has manyapplications. Wires made from some special materials melt quickly and break when large electric currents are passed through them. These materials are used formaking electric fuseswhich prevent fires and damage toelectric appliances. When an electric current flows through a wire, itbehaves like a magnet.

Electric Circuit: A complete pathway of the flowof electric current. Component of Electric Circuit: Component ofelectric circuit arefollowing : Cell: Provides energy forthe current toflow. Bulb: Lights upswhen an electric current flows through it. Switch: Keeps thecircuit off or on. Connecting wires: Help to conduct the electric current and complete thecircuit.

Effects of Electric Current:

Heating Effect: The wire gets hot when an electric current passes through it. This is the heating effect of theelectric current. Electric heater contains a coil ofwire called element which becomes redhot when current passes through it.The amount ofheat produced in a wire depends on its material, length and thickness.

Fuse: It is asafety device which prevents damage toelectric circuit. Itis made by inserting a shortwire into porcelain or insulating material.

MCB: Stands for Miniature Circuit Breakers. These are switches which automatically turn

offwhen current ina circuit exceeds the safe limit.

Magnetic Effect: When electric current passes through a wire, it behaves like a magnet. Thisis the magnetic effect of theelectric current. Thiswas first observed by Hans Christian Oersted. A current carrying coil of aninsulated wire wrapped around a piece of iron iscalled an electromagnet.

Electromagnet: An electromagnet is a coil of wire wound on a soft iron core, used to separate magnetic material fromthe junk. Doctors use tiny electromagnets to take outsmall pieces ofmagnetic material thathave accidentally fallen in the eye.Many toys also have electromagnets inside them.