Explanation

• In the photoelectric effect, electrons are emitted only when the frequency of incident light reaches a minimum threshold value.
• This minimum frequency is called the threshold frequency.
• Below this value, no electrons are emitted regardless of light intensity.
• This phenomenon was explained by Albert Einstein.

Last verified on 13-05-2026

Explanation

• Spring tides occur when the Sun, Earth, and Moon are aligned in a straight line.
• Their gravitational forces combine and produce very high and very low tides.
• These tides happen during full moon and new moon.
• They are the strongest type of tides.

Last verified on 13-05-2026

Explanation

• Rising factory output directly increases energy consumption in the industrial sector.
• Factories use energy for machines, production processes, and heating.
• So when production increases, industrial energy demand also increases.
• This sector is the largest consumer of commercial energy in most economies.

Last verified on 13-05-2026

Explanation

• Natural gas is widely used as a domestic fuel because it is easy to use and burns cleanly.
• It produces less smoke and fewer harmful gases compared to coal and other fuels.
• It is supplied through pipelines, making it convenient for households.
• It is considered a cleaner fossil fuel.

Last verified on 13-05-2026

Explanation

• Solar energy is obtained directly from sunlight using solar panels.
• It is a renewable and inexhaustible source of energy.
• It can be used for electricity, heating, and many daily applications.

Last verified on 13-05-2026

Explanation

• Cytoplasm is the living, jelly-like material inside the cell.
• All cell organelles are embedded within it.
• It helps in transport of materials and supports cellular activities.
• It is essential for the proper functioning of the cell.

Last verified on 13-05-2026

Explanation

• Carbohydrates are the main energy-giving nutrients in an ordinary diet.
• They are broken down into glucose, which provides energy to the body.
• They are the fastest and most efficient source of energy.
• Common foods rich in carbohydrates include rice, bread, and potatoes.

Last verified on 13-05-2026

Explanation

• Laser light is highly concentrated in a very narrow beam.
• This allows it to deliver a large amount of energy to a very small area.
• It does not spread out like normal light.
• This property makes lasers useful in medicine, industry, and communication.

Last verified on 13-05-2026

Explanation

• Atoms that have the same number of neutrons but different atomic numbers are called isotones.
• They belong to different elements because their proton numbers are different.

Additional information:

• The word “isotone” comes from Greek meaning “equal tension.”
• Isotopes belong to the same element, while isotones belong to different elements.

Last verified on 13-05-2026

Explanation

• Alpha radiation has the lowest penetrating power.
• It can be stopped easily by paper or even human skin.
• Alpha particles are heavy and carry a positive charge.

Additional information:

• Gamma rays have the highest penetrating power.

Last verified on 13-05-2026