Electronics (For HBL 19 July 2022)

In a electrical wire, it contains materials that are either conductors or insulators.

Which of the following materials do you think is most likely used to conduct electricity in a wire?

• Gold

• Steel

• Copper

• Graphite

Answer explanation

Why copper? It is because copper has superior conductivity and thus more efficient in carrying electrical current.

Why not steel? After all it can conduct electricity as well. Have you tried bending steel lately?

Although Graphite (like the pencil lead) is also a conductor, it is inflexible and brittle (breaks easily). They will make terrible wires!

Now gold is a good conductor as well and has good malleability (change in shape). So why not gold?

Basic answer --> $$$$

Now you see your friend lying on the floor - unconscious. He is grabbing on to an exposed electrical wire and you do not have the time to search for the emergency electrical cut-off switch.

You have to find a way to remove the wire from his hands. You look around you and you see the following:

A metal ruler

A pail of water (To wake him up?)

A metallic-looking rod (it looks plastic)

and a wooden broom.

Which would you use?

• 
• 
• 
• 

Answer explanation

Basically this question is about knowing which item is made of an insulator.

Clearly, the metal ruler is out of the question, given that metal conducts electricity!

Same goes for the metallic-looking rod. Though it may look like plastic, some plastic rods actually use aluminum (metal) foil as its outer covering! So no no.

If pouring water on your friend to wake him up sounds like a fun idea, do remember, water is also a conductor of electricity. If the water puddle reaches you....... (Sizzling sound).

Logically, a wooden broom will be the best since it is made of wood and it is actually an insulator.

Of course, by right, the first thing to do is to call SCDF (995) in such situations. I guess it depends on how good a friend he is, eh?

The video on the left shows wires being soldered on to a circuit board. The process of soldering is to ensure electronic components like wires are joined together to ensure they do not move out of place.

Do you think that the material (the solder) used to join the wire in place are conductors or insulators?

• Conductor,

  since need to ensure that electricity is able to continue flowing from the wire to the circuit board.

• Insulator,

  so that the user is not accidentally electrocuted from the exposed wire.

This is André-Marie _____.

He is the French physicist who founded and named the science of electrodynamics, now known as electromagnetism.

He also gives his name to the measurement of electrical current. What is his last name (in blank above)?

• Ohm

• Ampère

• Volta

• Faraday

Answer explanation

Ampere is the unit we use to measure electrical current.

Georg Simon Ohm - Discovered Ohm's Law on electrical resistance.

Alessandro Volta - The first man to discover voltage.

Michael Faraday - The English scientist who contributed to the study of electromagnetism and electrochemistry. Famous for his Faraday's cage (example in the video on the left.

Arrange the following battery sizes from smallest to largest.

• 
• 
• 
• 
• 

Answer explanation

The order is as to the left. Btw, button battery = coin battery.

What symbol was used to inform the potential difference in the battery??

• A

• V

• It was never indicated. Trick question.

Answer explanation

Potential difference = Voltage

Symbol for Voltage = V

Have to be clear the difference between

Current - "A"

Voltage - "V"

Resistance - Ohm (symbol on left)

What is the purpose of switches?

• To direct the electrical current to another circuit.

• To open or close an electrical circuit.

• To allow a switch of electrical component.

• To increase or decrease the electrical current within the circuit.

Answer explanation

Don't think too much. A switch is a switch.

Match the following switches to its names.

• Slide switch

• 
• Rocker switch

• 
• Toggle switch

• 
• Push button switch

• 
• Reed switch

• 

Answer explanation

The way the switches are activated speaks for itself.

The image on the left explains how reed switches work. It depends on magnetic attraction to keep the circuit open or close.

Can you think of any application that works like that?

Picture on the left shows an LED. What is an LED?

• Light Emitting Dots

• Little Emitting Diode

• Light Emitting Diode

• Light Emergency Device

Which of the following is true comparing LED and light bulbs?

(See photo on left for an example of a light bulb)?

• LEDs are more efficient than light bulbs.

• LEDs emit lesser heat than light bulbs

• LEDs can last longer than light bulbs

• LEDs are easier to replace when blown.

• LEDs are generally more environmentally friendly than light bulbs.

Answer explanation

Actually since LEDs emit less heat and can last longer, they are therefore more efficient and environmentally friendly!

LEDs are however more troublesome to replace since they don't generally come in holders much like how light bulbs too. Look on left to see what I mean!