Explanation

A bolometer is a device for measuring radiant heat by means of a material having a temperature-dependent electrical resistance.

Bolometer was invented in 1878 by Samuel Pierpont Langley (American astronomer)

Explanation

In solids, heat transfer occurs primarily through conduction, where vibrations and collisions of particles (atoms or molecules) transfer energy from one point to another.

Explanation

Explanation

• The Candela (cd) is the SI unit of luminous intensity.
• It is defined as the luminous intensity of a monochromatic source that emits light at a frequency of 540 x 10^12 Hz with a luminous efficiency of 683 lm/W.

Explanation

Wavelength is a measure of distance between two wave crests or troughs.

The SI unit for measuring distance is the meter (m), hence it is used for wavelength.

It is typically denoted by the symbol λ (lambda).

Explanation

• The principal axis is a horizontal line that passes through the centre of the lens, perpendicular to its surface.
• It is the central axis around which the lens is symmetrical.

Explanation

A magnifying glass uses a convex lens to enlarge the appearance of objects.

Convex lenses converge light rays to a focal point, producing a magnified image.

Explanation

• The formula of Density is: D=m/v
• ****
• Here D is density,
• M is mass &
• V is Volume.
• Density is commonly expressed in units of grams per cubic centimeter.
• The standard units are kg/m³
  

Explanation

Explanation

Potential energy is the stored form of energy in an object, which can be released when the object is moved, stretched, or compressed.

Examples:

• Gravitational potential energy (e.g., a ball at the top of a hill)
• Elastic potential energy (e.g., a stretched rubber band)
• Electrical potential energy (e.g., a charged battery)