Explanation

• All electromagnetic waves (like light, X-rays, and radio waves) travel through a vacuum at the same constant speed.
• It is approximately 3 × 10⁸ meters per second.
• This speed is known as the speed of light in a vacuum.

Last verified on 31-10-2026

Explanation

μ = Frictional Force / Normal Force

μ = Newton / Newton

Newton cancels, so it has no unit. It is dimensionless.

Last verified on 26-10-2026

Explanation

• A scalar quantity has magnitude only and no direction.
• Speed tells us how fast an object moves, without specifying its direction.

Additional information:

• Velocity, acceleration, and force are vector quantities because they have both magnitude and direction.

Last verified on 31-10-2026

Explanation

• Newton’s First Law of Motion is also called the Law of Inertia.
• It states that an object remains at rest or continues moving at a constant velocity in a straight line unless acted upon by an unbalanced external force.
• Inertia is the tendency of an object to resist changes in its state of rest or motion.
• Proposed by: Sir Isaac Newton in Principia Mathematica (1687).

Last verified on 15-10-2026

Explanation

• Power is the rate of doing work or the rate at which energy is transferred.
• It is a scalar quantity (has magnitude only).
• It shows how quickly work is done.
• The SI unit of power is the Watt (W).
• 1 Watt = 1 Joule per second (1 W = 1 J/s).

Additional information:

• Formula: P = W/t = E/t
• SI Base Unit: kg·m²·s⁻³
• Dimension Formula: ML²T⁻³
• James Watt is the scientist after whom the Watt unit is named.

Last verified on 09-07-2026

Explanation

• Displacement is the straight-line change in position from an initial point to a final point.
• It is a vector quantity, having both magnitude and direction.

Last verified on 31-10-2026

Explanation

• At the center of the Earth, g = 0.
• Gravity from all directions cancels out at the center.
• So net gravitational force becomes zero.
• An object would feel weightless there.
• This is due to symmetrical distribution of Earth's mass.
• Earth’s surface gravity: 9.8 m/s²

Last verified on 17-06-2026

Explanation

• All electromagnetic waves travel through a vacuum at 3x10^8 m/s.
• This is the speed of light (c).
• Radio waves, microwaves, visible light, X-rays and gamma rays all have the same speed in vacuum.

Last verified on 31-10-2026

Explanation

• Salmonella Typhi is the bacterium responsible for typhoid fever.
• It is a Gram-negative, rod-shaped bacterium.
• It spreads through food or water contaminated with the feces of an infected person.
• Common symptoms include prolonged fever, headache, weakness, abdominal pain, and digestive problems.
• Typhoid can be prevented through safe drinking water, proper sanitation, handwashing, and vaccination.

Last verified on 31-10-2026

Explanation

• Restriction enzymes are also called molecular scissors because they cut DNA at specific recognition sequences.
• They recognize particular short DNA sequences, often 4–8 base pairs long.
• These enzymes may produce sticky ends or blunt ends after cutting DNA.
• They are widely used in genetic engineering, recombinant DNA technology, and gene cloning.
• Example: EcoRI is a restriction enzyme that recognizes the sequence GAATTC.

Last verified on 31-10-2026