Explanation

Nuclear fusion reactions in a star's core produce outward thermal pressure, which balances the inward pull of gravity.

This balance between gravitational force and nuclear pressure keeps the star stable and prevents collapse during its main life phase.

Explanation

 A proton is a fundamental particle found in the nucleus of an atom.

Its mass is relatively large compared to other particles like electrons, but smaller than some other subatomic particles.

Mesons are a type of particle made up of a quark and an antiquark.

Their mass range varies, but generally falls between that of a proton and an electron.

Some mesons, like the very heavy upsilon mesons, can have a mass significantly greater than a proton. 

Explanation

The dead time of a GM counter is the brief period (about 10⁻⁴ seconds) after detecting a particle during which it can't detect another.

This happens because the detector needs time to reset.

It limits how fast the counter can measure radiation.

Explanation

The word "transistor" is derived from "transfer" and "resistor".

It signifies the transfer of resistance — specifically, it controls a large output resistance using a small input resistance.

In essence, a transistor transfers a signal from a low-resistance circuit to a high-resistance circuit, acting as an amplifier or switch.

Explanation

Electronic transitions occur when electrons jump between energy levels in an atom.

These transitions typically release photons in the infrared, visible, or ultraviolet regions — depending on the energy difference.

γ-radiations (gamma rays) are high-energy photons emitted from the nucleus, not from electronic transitions.

They are associated with nuclear reactions, not electronic energy level changes.

Explanation

 A PN junction diode allows current to flow only in one direction — from P to N (forward bias).

During the positive half cycle of AC, the diode is forward-biased (low resistance), so current flows.

During the negative half cycle, the diode is reverse biased, so it blocks current and offers high resistance.

Explanation

 A ray of light represents the direction of propagation of the wave.

A wavefront is a surface over which the phase of the wave is constant.

Rays are always perpendicular to the wavefronts.

Explanation

In projectile motion, the velocity is maximum at the point of projection and just before hitting the ground,

Because that’s where the full initial speed is present (both vertical and horizontal components).

At the highest point, the vertical component becomes zero,

And only the horizontal velocity remains, so the overall speed is less than at the point of projection.

Explanation

To find the resultant of two forces acting at right angles, use the Pythagorean theorem:

Resultant = √(3² + 4²) = √(9 + 16) = √25 = 5N

Explanation

Volume of a sphere (or similar 3D object):

V= 4/3​πr^3

• So, volume depends on the cube of the radius.

• Percentage error in volume = 3 × (percentage error in radius)

$$\text{Error in volume}=3\times 1\%=3\%$$