Explanation

Total internal reflection occurs when a light wave reaches the boundary between a denser medium and a rarer medium.

All of the light is reflected back into the denser medium.

Explanation

Security scanners used at night typically employ infrared (IR) technology to detect heat signatures, allowing for nighttime surveillance.

IR waves have a longer wavelength than visible light, making them ideal for detecting heat radiation from objects or people.

Explanation

A centrifuge is a machine that uses centrifugal force to separate particles of different densities or sizes from a mixture.

It is commonly used to separate:

• Liquids from solids (e.g., mud, sludge)
• Heavy particles from lighter particles (e.g., sedimentation)
• Immiscible liquids (e.g., oil and water)

Explanation

Soap is a type of salt that is formed from the reaction of a fatty acid with an alkali, such as sodium or potassium hydroxide.

Fatty acids are long-chain carboxylic acids that are found in fats and oils.

Explanation

Temporary hard water is caused by the presence of dissolved calcium and magnesium bicarbonates (Ca(HCO3)2 and Mg(HCO3)2).

These salts are commonly found in natural water sources and can enter the water supply through contact with limestone, dolomite, and other mineral deposits.

Explanation

Explanation

When a radioactive nuclide emits a beta (β) particle, it undergoes beta decay.

In beta decay, a neutron in the nucleus is converted into a proton and an electron (the beta particle).

As a result, the atomic number (proton number) of the nucleus increases by 1.

Explanation

A magnetic compass is a device that responds to the presence of a magnetic field by aligning its needle with the direction of the field.

It is a common tool used to detect and measure magnetic fields.

Explanation

Ohm's Law states that the current (I) flowing through a conductor is directly proportional to the voltage (V) applied across it, and inversely proportional to the resistance (R) of the conductor.

Mathematically, this is expressed as: I = V/R Or, V = I × R

This means that as the voltage increases, the current increases, provided the resistance remains constant.

Explanation

Abrasives are substances that wear away or remove material through friction or rubbing.

Examples of abrasives include:

Water insoluble minerals like:

• Silica (sand)
• Alumina (aluminum oxide)
• Calcium carbonate (limestone)
• Diamond