Explanation

• Iron filings are attracted to the magnetic field of a magnet.
• The magnetic field is strongest at the poles of the magnet.
• Therefore, the iron filings will be attracted more at the poles of the magnet, where the magnetic field is most intense.
• This is why you'll often see iron filings forming a pattern that traces out the magnetic field lines, with the filings clustering at the poles.

Explanation

• The Moon is illuminated because it reflects the light from the Sun.
• The Moon's surface reflects the sunlight, making it visible to us on Earth.

Explanation

• A nail cutter is an example of a Second-class lever.
• Where the load (the nail) is located between the effort (the hand) and the fulcrum (the pivot point of the cutter).

Explanation

According to the World Health Organization (WHO), the industrial limit of sound in industries must be 75 dB (Decibels).

Explanation

The property that doesn't typically apply to solids is "Solids have an indefinite volume."

Explanation

In a fusion reactor, it is necessary to overcome the electrostatic repulsive force between nuclides (nuclei) in order to achieve fusion. This requires:

• Very high temperature: Fusion reactions occur at extremely high temperatures, typically around 150 million degrees Celsius (270 million degrees Fahrenheit). This energy is needed to overcome the electrostatic repulsive force and bring the nuclei close enough together to fuse.
• Very high pressure: Fusion reactions also require incredibly high pressure, similar to those found at the core of the sun. This pressure helps to overcome the repulsive force and increase the likelihood of fusion.
• Very small volume: The reaction chamber in a fusion reactor is designed to be extremely small, which helps to increase the density of the plasma (ionized gas) and reduce the distance between the nuclei. This makes it easier to overcome the electrostatic repulsive force and achieve fusion.

Explanation

Farad (F) is the unit of capacitance.

It is equal to Coulomb/Volt.

From Ohm’s Law and unit analysis: Second/Ohm = s/Ω = Farad (F)

Explanation

An insulator has a completely filled valence band. 

Explanation: In an insulator, all the valence electrons are tightly bound to their atoms and cannot move freely, resulting in a filled valence band.

Since there are no electrons available in the conduction band, they cannot move to it and conduct electricity. 

Explanation

In an ideal gas, it is assumed that there are no intermolecular forces between molecules.

Hence, the potential energy associated with the molecules is considered zero.

Explanation

An ideal op-amp has very high input resistance, often in the megaohms range.

This prevents it from drawing current from the input source.