Electricity: Magnetic and Heating Effects — Grade 8 (Curiosity)

Vocabulary flashcards covering key terms and concepts from Chapter 4: Electricity: Magnetic and Heating Effects (Grade 8).

Magnetic effect of electric current

When electric current flows through a conductor, it produces a magnetic field around it.

Magnetic field

The region around a magnet or a current-carrying wire where its magnetic influence can be felt.

Electromagnet

A coil of wire that becomes a magnet when current passes through it, strengthened by an iron core.

Lifting electromagnet

A strong electromagnet used in cranes to lift and release metal objects by switching current ON and OFF.

Polarity of an electromagnet

The two ends of the coil act as opposite poles (North and South); polarity can be reversed by changing the current direction.

Strength of an electromagnet

Increase with higher current and more turns; an iron core also strengthens the magnetic field.

Oersted

Danish scientist who showed that electricity and magnetism are linked by observing compass deflection from a current.

Voltaic cell (Galvanic cell)

A device that generates electricity from chemical reactions between two different metals and an electrolyte.

Electrodes

The metal plates in a Voltaic cell that participate in the chemical reaction (electrode 1 and electrode 2).

Electrolyte

The liquid or solution inside a cell that enables ion flow and chemical reactions.

Dead battery

A battery that has exhausted its chemicals and can no longer supply electricity.

Dry cell

A disposable cell with a zinc container (negative terminal), a carbon rod (positive terminal), and a paste-like electrolyte.

Rechargeable battery

A battery that can be recharged and reused multiple times.

Lithium-ion battery

A common rechargeable battery using lithium and cobalt with high energy density.

Solid-state battery

A future or emerging rechargeable battery using solid electrolytes for improved safety and performance.

Lemon cell

A simple Voltaic cell using lemon juice as electrolyte with copper and iron electrodes to produce electricity.

Electrodes and electrolyte (Voltaic lemon cell in practice)

Copper/wire and iron/nail as electrodes; lemon juice acts as electrolyte to conduct ions.

Dry cell structure

Zinc container (negative), carbon rod (positive), with a paste-like electrolyte; designed for single use.

Heating effect of electric current

Generation of heat in a conductor when current flows due to resistance.

Resistance

Opposition to the flow of electric current; materials differ in resistance, affecting heat produced.

Nichrome wire

A high-resistance alloy used as a heating element; it heats up more than copper of the same size.

Heating element

Rod or coil inside appliances that converts electrical energy into heat.

Applications of heating effect

Used in room heaters, stoves, irons, immersion heaters, kettles, hair dryers, and industrial furnaces.

Energy losses in transmission

Overheating of wires during transmission causing energy loss; safety devices help prevent this.

Earth’s magnetic field

Global magnetic field generated by moving liquid iron in Earth’s core; aids navigation and shields life.

Electromagnetism (electricity–magnetism link)

The interconnection between electricity and magnetism; changing electric current creates magnetism, and changing magnetism can induce current.

LED glow test (in lemon cell demonstration)

A glowing LED indicates the cell is producing current; incorrect polarity may prevent it from glowing.