Explanation

The outermost layer of the Sun is called the corona.

It is the Sun's outer atmosphere, extending millions of kilometers into space and visible during a total solar eclipse.

The innermost layer is the core, where nuclear fusion occurs.

Explanation

The direction of induced e.m.f. (electromotive force) in a circuit is determined by Lenz's law.

It states that the induced e.m.f. will oppose the change in magnetic flux that induced it.

This is a consequence of the conservation of energy.

Explanation

Magnetic poles always exist in pairs, with every magnet having a north pole and a south pole.

Like poles (north-north or south-south) repel each other.

Unlike poles (north-south or south-north) attract each other.

Explanation

Electromagnetic waves are typically listed in order of increasing wavelength (or decreasing frequency) as follows:

• Gamma-rays (shortest wavelength, highest frequency)
• X-rays
• Microwaves (longer wavelength, lower frequency)

Explanation

Sound is a form of mechanical energy that is produced by vibrations or oscillations of particles in a medium, such as air, water, or solids.

When an object vibrates, it creates a disturbance in the medium around it, causing the particles to oscillate back and forth.

This oscillation, or wave motion, is what we perceive as sound.

Explanation

The gravitational force between two masses is mutual; each mass exerts an equal and opposite force on the other,.

It aligns with Newton's 3rd law of motion: for every action, there is an equal and opposite reaction.

Explanation

To find the pressure, you need to divide the force (20 N) by the area (5 cm^2).

Since 1 cm^2 = 0.0001 m^2, the area in square meters is:

5 cm^2 x (0.0001 m^2/cm^2) = 0.0005 m^2

Now, you can calculate the pressure:

Pressure = Force / Area = 20 N / 0.0005 m^2 = 40,000 N/m^2

Since 1 N/m^2 = 1 Pascal (Pa), you can convert the pressure to N/cm^2:

40,000 N/m^2 x (1 m^2 / 100 cm^2) = 4 N/cm^2

Explanation

Inclined planes are used to move heavy loads over vertical obstacles.

The inclined plane is one of the six classical simple machines defined by Renaissance scientists. 

ND20-1-2023

Explanation

At the highest point of a projectile's motion:

- Its velocity is purely horizontal (vertical component = 0).

- Its acceleration is still vertically downward due to gravity.

So, the velocity vector is horizontal, and the acceleration vector is vertical ⇒ they are perpendicular.

∴ Angle between velocity and acceleration = 90°  

Explanation

As a rocket moves upward, its acceleration increases continuously. 

This is because as the rocket burns fuel and expels exhaust gases, its mass decreases.

According to Newton's second law of motion (F = ma), with a constant force (the engine's thrust), a decreasing mass results in an increasing acceleration.