Explanation

Copper, silver, aluminum, gold, steel, and brass are common conductors of electricity.

The most highly conductive metals are silver, copper, and gold

Silver is the first-best conductor of heat.

Copper is the second-best conductor of heat.

Explanation

The relation between work (W) done and torque (τ) in rotational motion is:

W = τdθ

Where:

- W is the work done

- τ is the torque

- dθ is the angular displacement

This shows that work done in rotational motion is the product of torque and angular displacement.

Explanation

The microscopic form of Ohm's law is:

J = σE

where J is the current density.

σ is the conductivity.

E is the electric field.

Explanation

Increasing the energy of a sound wave amplifies its amplitude, resulting in a louder sound.

Loudspeakers work by converting electrical energy into sound energy, so higher energy input leads to a louder output.

Explanation

The product RC (Resistance × Capacitance) gives the time constant in an RC circuit.

Its unit is Ohm × Farad = seconds (s), which is the unit of time.

Explanation

Freons (CFCs) and halons are stable in the troposphere but break down under UV light in the stratosphere.

This breakdown releases chlorine and bromine, which destroy ozone molecules in the ozone layer.

Explanation

The relation between alpha (α) and beta (β) is given by:

β = α / (1 - α)

Given α = 1/2:

β = (1/2) / (1 - 1/2)

= (1/2) / (1/2)

= 1

Explanation

The relation between the coefficient of volume expansion (γ) and the coefficient of linear expansion (α) is: γ = 3α

This relation holds true for isotropic solids.

The coefficient of volume expansion is approximately three times the coefficient of linear expansion.

Explanation

The principal axis is a straight line passing through the center of curvature and the pole of a spherical mirror.

It serves as the reference line for measuring distances and analyzing image formation in mirrors.

Explanation

• The speed of sound in air at 0°C (32°F) is 332 meters per second.

The speed of sound in different materials:

• Air: 332 m/s
• Sea water: 1530 m/s
• Lead: 2160 m/s
• Gold: 3240 m/s
• Brick: 3650 m/s
• Copper: 4760 m/s
• Glass: 5100 m/s
• Aluminium: 6420 m/s