Explanation

The cooling fins at the back of a refrigerator are typically made of a black, rough surface to maximize heat radiation. This design:

• Increases the surface area for heat transfer
• Absorbs heat from the surrounding air
• Emits heat more efficiently due to the rough surface

Explanation

The radioactive decay equation shows a parent nucleus (91Pa^233) decaying into a daughter nucleus (92U^233) with the emission of a particle.

The parent nucleus has an atomic number of 91 (Protactinium), and the daughter nucleus has an atomic number of 92 (Uranium).

This increase in atomic number indicates that a beta particle (β) has been emitted.

Explanation

To determine the symbol of element B with five protons and six neutrons, we can follow these steps:

The number of protons (atomic number) determines the element. An element with five protons is boron (B).

The mass number (A) is the sum of protons and neutrons. For this element, it is 5 + 6 = 11.

Therefore, the symbol for this element is 11B.

Explanation

The atomic mass (also known as atomic weight) of an element is the total mass of protons and neutrons present in the nucleus of an atom.

This includes:

• Mass of protons (which defines the element)
• Mass of neutrons (which varies in different isotopes)

Explanation

• If the area of the parallel plate capacitor is doubled, the capacitance will also double.
• The capacitance of a parallel plate capacitor is directly proportional to the area of the plates: C = ε × (A/d)
  

Explanation

The direction of the electric force (F) and electric field intensity (E) are parallel to each other.

The electric field intensity is a vector quantity that points in the direction of the force that would be experienced by a test charge at a given point.

Explanation

Sound waves require a physical medium, such as air, water, or solid objects, to propagate.

They cannot travel through a vacuum because there are no particles to transmit the energy.

Explanation

The velocity of a satellite is independent of its mass.

According to Kepler's laws, velocity is determined by the orbit's semi-major axis and the central body's gravitational constant (G), not by the satellite's mass.

Explanation

Newton's law of universal gravitation states that every point mass attracts every other point mass by a force acting along the line intersecting both points.

This law applies to all objects in the universe, regardless of their size, shape, or composition.

Explanation

When a body is in unstable equilibrium, a slight tilt will cause its center of gravity (CG) to remain above the point of contact, making it prone to toppling over or falling.

This means that the CG is not directly over the point of support, but is still above it, creating a moment that tends to rotate the body further.

Key Points:

• A body is in stable 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.