What happens to a compass needle near a current-carrying wire?
It deflects.
What is the magnetic effect of electric current?
The production of a magnetic field around a conductor.
What happens when current stops in the wire?
The magnetic effect disappears.
In which year did Oersted make his discovery?
1820.
What is the region of detectable magnetic effect called?
A magnetic field.
What is a compass needle?
A tiny magnet.
What does compass deflection near a wire show?
The wire's magnetic field acts on the compass needle.
What is a current-carrying coil that behaves as a magnet called?
An electromagnet.
What happens to a cylindrical coil when current passes through it?
It behaves like a magnet.
What is the effect on nearby magnetic compasses?
Their needles are deflected.
What does inserting an iron nail into the coil core do?
It makes the coil a stronger magnet.
What happens to compass needle deflection after adding an iron nail?
The deflection increases.
What does an electromagnet attract when current flows?
Iron paper clips.
What happens to an electromagnet's magnetic effect when current stops?
It is lost.
How many poles does an electromagnet have?
Two poles.
How can an electromagnet be made stronger?
Increase the current or coil turns.
What does a battery with more cells produce?
A larger current.
How are electromagnet poles reversed?
By reversing the current direction through the coil.
What happens when a lifting electromagnet is switched on?
It lifts iron or steel objects.
What happens when a lifting electromagnet is switched off?
It releases the objects.
Name one device that uses electromagnets.
An electric bell.
What is the heating effect of electric current?
The warming of a conductor by current.
After about 30 seconds, what happens to a nichrome wire?
It feels warm.
What converts electrical energy into heat in a conductor?
Resistance does.
Which wire has higher resistance, nichrome or copper of same size?
Nichrome has higher resistance.
What factors does heat generated in a wire depend on?
It depends on the wire's material, thickness, length, and current duration.
Why does a nichrome wire heat more with 2 cells?
Because the current is greater.
Why does an incandescent lamp glow?
Its filament is heated by an electric current.
Which appliances work on current's heating effect?
Electric heaters, stoves, kettles, irons, immersion rods, and hair dryers.
What is the heating element?
The heated rod or coil inside a heating appliance.
What may the heating element look like in some appliances?
It can glow red hot.
What can current's heating effect cause in transmission wires?
Energy loss and overheating of plugs and sockets.
What can overheated plugs and sockets do?
They may melt plastic parts or cause fires.
What should be used to prevent unnecessary heating in switchboards?
Wires, plugs, and sockets rated for the specified current.
What two metal rods are in a Voltaic cell?
Two rods of different materials.
What is the liquid in a Voltaic cell called?
The electrolyte.
What produces electricity in a Voltaic cell?
A chemical reaction between the electrodes and the electrolyte.
Where does current flow when the circuit is connected?
From the positive terminal through the circuit to the negative terminal.
What happens when Voltaic cell chemicals are used up?
The cell becomes dead and can no longer supply electricity.
What acts as electrodes in a lemon cell?
Copper wire and an iron nail.
What acts as the electrolyte in a lemon cell?
Lemon juice.
What shows a lemon cell is working?
A glowing LED.
What is the electrolyte in a dry cell like?
It is a thick moist paste.
Which dry-cell part is the negative terminal?
The zinc container.
Why must a dry cell be disposed of after use?
It is a single-use cell.
What batteries can be recharged and reused multiple times?
Rechargeable batteries.
Which rechargeable battery type is most common today?
Lithium-ion batteries.
Where should used batteries be sent for recycling?
Special e-waste recycling facilities.
Which devices commonly use rechargeable batteries?
Watches, phones, laptops, tablets, inverters, and electric vehicles.
Why do rechargeable batteries not last forever?
They slowly wear out after many charge and use cycles.
Test your knowledge with 22 questions on Electricity Magnetic and Heating Effects.
1. A compass needle deflects near a current-carrying wire but returns to its original direction when the current stops; what does this show about the wire’s magnetic effect?
2. What is meant by the magnetic effect of electric current?
Review the complete course in the revision sheet for Electricity Magnetic and Heating Effects.
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