Explanation

Pressure is constant → use Charles's Law: V₁/T₁ = V₂/T₂  

Given:  

V₁ = 3.0 L, T₁ = 300 K, T₂ = 450 K  

V₂ = V₁ × T₂ / T₁  

V₂ = 3.0 × 450 / 300  

V₂ = 1350 / 300 = 4.5 L

So when temp goes from 300 K to 450 K, volume increases from 3.0 L to 4.5 L.

Last verified on 26-06-2026

Explanation

• Electric current is the flow of electric charge.
• In metals, this charge is mainly carried by electrons.
• Current is measured in amperes (A).
• Without charge movement, there is no electric current.

Last verified on 25-06-2026

Explanation

• CFCs, carbon dioxide (CO₂), and methane (CH₄) are all greenhouse gases.
• Carbon dioxide traps heat in the atmosphere and increases temperature.
• Methane is a very strong greenhouse gas with high warming effect.
• CFCs also damage the ozone layer and act as greenhouse gases.

Last verified on 16-06-2026

Explanation

• White clothes are worn in hot climate because they reflect most of the sunlight and absorb very little heat.
• This helps keep the body cool in high temperatures.
• Dark colors like black absorb more heat, making the body warmer.

Last verified on 25-06-2026

Explanation

• A rectifier is an electrical device that converts Alternating Current (AC) into Direct Current (DC).
• It allows current to flow in only one direction.
• It is commonly used in power supplies and chargers.
• Rectifiers use components like diodes for conversion.

Last verified on 25-06-2026

Explanation

• The retina is composed of light-sensitive neurons (photoreceptors).
• It detects light and converts it into nerve signals sent to the brain.
• It contains two main cells: rods and cones.
• These cells help in vision, color detection, and low-light vision.

Last verified on 25-06-2026

Explanation

• Electric fire alarms work on the principle of expansion of metals due to heat.
• A fire alarm uses a bimetallic strip that bends when heated because different metals expand at different rates.
• This bending completes an electric circuit and activates the alarm.
• It is an example of the thermal expansion principle.

Last verified on 25-06-2026

Explanation

• Pneumatics is the study of the mechanical behavior and application of gases, especially compressed air, under pressure.
• It deals with the use of pressurized gases to produce mechanical motion.
• Pneumatic systems are commonly used in machines, tools, and industrial equipment.
• The word comes from the Greek word "pneuma" meaning air or breath.

Last verified on 25-06-2026

Explanation

• Opposite electrostatic charges attract each other.
• Positive (+) and negative (−) charges pull toward each other due to electrostatic force.
• Like charges (positive-positive or negative-negative) repel each other.
• This principle is explained by Coulomb’s Law.

Last verified on 25-06-2026

Explanation

• Lamp is not a form of energy.
• It is a device that produces light.
• Heat, sound, and light are all different forms of energy.
• Energy is the ability to do work or produce change.
• A lamp converts electrical energy into light energy.

Last verified on 16-06-2026