Explanation

To obtain greater dispersion by a diffraction grating, the slit separation should be decreased. 

Dispersion:

• In diffraction gratings, dispersion is the separation of light wavelengths during diffraction, with greater dispersion resulting in wider color separation.

Slit separation:

• The distance between individual slits on the grating is called the slit separation.

Relationship between slit separation and dispersion:

• Smaller slit separations lead to larger angles of diffraction for a given wavelength, resulting in greater dispersion.
• Imagine the light waves as being "bent" more by the closer slits, causing them to spread out further

Explanation

Rotational kinetic energy of a disc about its center:  

K.E = (1/2) I ω², where I = moment of inertia.

For a disc, I = (1/2)MR²,  

So, K.E = ½ × (½ MR²) × ω² = ¼ MR²ω²

If linear velocity v = Rω, then  

K.E = ¼ Mv²

Explanation

Joule is a derived unit of energy, not a base unit.

Kelvin (temperature), Kilogram (mass), and Ampere (current) are SI base units.

Explanation

In Simple Harmonic Motion (S.H.M.), frequency is a constant and does not depend on the particle's position (mean or extreme).

• At the mean position, the velocity is maximum, and the acceleration is zero, but the frequency remains constant throughout the motion.

Explanation

If the direction of the magnetic field is reversed, the direction of the force exerted on a charged particle or a current-carrying wire will also be reversed.

This is because the force due to a magnetic field depends on the direction of the field.

The direction of the current or velocity, and the charge of the particle (if applicable).

Explanation

Metals are good conductors of electricity because they have free electrons, also known as conduction electrons or mobile electrons.

These electrons are not tightly bound to a specific atom and are free to move throughout the metal, carrying electrical current.

Explanation

The correct answer is: Light waves, Radio waves, Microwaves

This group consists only of electromagnetic waves, which are waves that propagate through the electromagnetic field.

They do not require a physical medium to propagate.

Explanation

When a body is tilted slightly, if its center of gravity remains above the point of contact, it will tend to return to its original position, restoring equilibrium.

This is a characteristic of stable equilibrium.

Key Points:

• A body is in unstable equilibrium after slight tilt if its center of gravity remains above the point of contact.
• A body is in neutral equilibrium when its center of gravity remains at same height.

Explanation

Light waves are electromagnetic waves that can travel through a vacuum without a medium.

They consist of oscillating electric and magnetic fields perpendicular to each other and the direction of propagation.

Explanation

 A spectrophotometer measures the amount of light absorbed by a substance at different wavelengths.

It is widely used in plant studies to analyze how leaves absorb specific wavelengths of light, which is crucial for understanding photosynthesis.