Physics Fundamentals | MCQs

Explanation

The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That's about 186,282 miles per second.

A universal constant is known in equations as "c," or light speed.

The speed of light in air is 2.9 × 10⁸ m/s.

Explanation

The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium.

Explanation

 A calorie is a unit of energy, specifically used to measure heat energy.

1 calorie is the amount of heat required to raise the temperature of 1 gram of water by 1°C.

In dietary terms, we use kilocalories (kcal) — where 1 kcal = 1000 calories — but it still measures energy, not diet or food itself

Explanation

Mercury is used as a thermometric fluid because it has several ideal properties:

1. High Boiling Point (B.P)

   • Mercury doesn't evaporate easily, which makes it suitable for measuring high temperatures.

2. Low Freezing Point (not high M.P)

   • Mercury has a low melting point (−38.83°C), which helps in measuring low temperatures, though this limits it in very cold environments.

3. Stable and Uniform Coefficient of Expansion

   • Mercury expands uniformly with temperature, which gives accurate and consistent readings.

4. Visibility and Non-wettability

   • Mercury is shiny and opaque, so it's easy to see in a glass tube.

   • It doesn't stick to glass, which keeps the readings clean and precise.

Explanation

Pascal (Pa) is defined as 1 Newton per square meter (N/m²).

It measures the amount of force applied over a unit area.

Explanation

 When a ball is thrown vertically upwards, its velocity decreases as it rises due to gravity.

At the maximum height, the velocity becomes zero before it starts to fall back down.

Explanation

The speed of sound in water is approximately 1500 m/s, which is slower than in most solid materials but faster than in air.

This speed can vary slightly depending on factors like temperature and salinity.

Explanation

The product of frequency and time period is always equal to 1.

This is because frequency = 1/time period, so their product is 1.

Explanation

 None of these options are completely incompressible.

While solids are the least compressible among the three states of matter (solid, liquid, and gas), all of them can be compressed to some degree. 

Explanation

Lamp is not a form of energy; it is a device that uses electrical energy to produce light.

Sound, Light, and Heat are all valid forms of energy.