The velocity of heat radiations in vacuum is

Options

A. equal to that of sound
B. equal to that of ultrasonic
C. equal to that of Infra sonics
D. equal to that of light

Explanation

To solve the question regarding the velocity of heat radiations in vacuum, we can follow these steps:

### Step 1: Understand the Nature of Heat Radiation
Heat radiation is a form of energy transfer that occurs through electromagnetic waves. It primarily falls within the infrared part of the electromagnetic spectrum.

**Hint:** Recall that electromagnetic radiation includes various types such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

### Step 2: Identify the Medium for Heat Radiation
Heat radiation, being electromagnetic in nature, does not require a medium to travel. It can propagate through a vacuum.

**Hint:** Remember that unlike sound waves, which require a medium (like air, water, or solids) to travel, electromagnetic waves can move through empty space.

### Step 3: Compare with Other Types of Waves
The question provides options that include sound, ultrasonics, infrasonics, and light. Sound, ultrasonics, and infrasonics are all mechanical waves that require a medium to propagate, while light (and thus heat radiation) can travel through a vacuum.

**Hint:** Think about the properties of sound waves and how they differ from electromagnetic waves.

### Step 4: Conclude the Velocity of Heat Radiation
Since heat radiation belongs to the electromagnetic spectrum and can travel through a vacuum, its velocity is the same as that of light in vacuum, which is approximately \(3 \times 10^8\) meters per second.

**Hint:** Recall the speed of light as a fundamental constant in physics.

### Final Answer
The velocity of heat radiations in vacuum is equal to that of light.

**Answer:** The velocity of heat radiation in vacuum is equal to that of light.