Explanation

An insulator has a completely filled valence band. 

Explanation: In an insulator, all the valence electrons are tightly bound to their atoms and cannot move freely, resulting in a filled valence band.

Since there are no electrons available in the conduction band, they cannot move to it and conduct electricity. 

Explanation

In an ideal gas, it is assumed that there are no intermolecular forces between molecules.

Hence, the potential energy associated with the molecules is considered zero.

Explanation

An ideal op-amp has very high input resistance, often in the megaohms range.

This prevents it from drawing current from the input source.

Explanation

In photovoltaic cells, the current increases with the intensity of incident light.

More light intensity means more photons, which release more electrons, generating higher current.

Explanation

The time period of a simple pendulum is independent of its mass.

It depends on length and acceleration due to gravity:

T = 2π√L/g

Explanation

According to the law of universal gravitation:

F ∝ (m1 × m2) / r^2

Initially, F0 ∝ (m × m) / r^2

After doubling the mass and halving the distance:

F_new ∝ (2m × 2m) / (r/2)^2

= 16 × F0

Explanation

The Fermi energy is the highest energy level that electrons occupy at absolute zero temperature.

Above this energy, states are empty, and below it, they are filled.

Explanation

Surface tension acts like a stretched membrane on the water's surface, and the surface tension along the blade's edges is greater than the blade's weight.

The force of surface tension acts tangentially to the liquid surface on the circumference of the blade.

Explanation

The moment of inertia depends on the mass of the object,

how the mass is distributed relative to the axis of rotation,

and the axis of rotation itself,

but it does not depend on the angular velocity.

Explanation

Louder sound is characterized by high amplitude.

Amplitude refers to the strength of the sound wave.

A higher amplitude results in a louder sound.