Explanation

• Testosterone is a steroid hormone that can cross the cell membrane and bind to intracellular receptors, specifically androgen receptors.
• This binding triggers gene transcription and protein synthesis, leading to various physiological responses.

Explanation

• Paracrine signaling is a type of cell signaling where cells communicate with each other through chemical signals, such as local hormones or neurotransmitters, that are released into the extracellular space and bind to receptors on nearby cells.
• This type of signaling is typically short-range and affects cells in a localized area.

Explanation

Wavelength of slow moving neutrons is about 10^-10 m.

Explanation

• A stone whirling in a horizontal circle on the end of a string is a classic example of a conical pendulum, a type of physical system that demonstrates principles of circular motion, centrifugal force, and angular momentum.
• The string traces out a cone-shaped path, hence the name "conical pendulum".
• This is different from a simple pendulum, which swings back and forth in a vertical plane.

Explanation

• Electrons exhibit diffraction effects because their de Broglie wavelength is similar to the spacing between atomic layers in a crystal.
• The de Broglie wavelength of an electron is given by λ = h/p, where h is Planck's constant and p is the electron's momentum.
• For electrons in a crystal, this wavelength is typically in the range of 0.1-1 nanometers, which is similar to the spacing between atomic layers in the crystal.
• As a result, electrons interact with the crystal lattice and exhibit diffraction effects, such as bending around corners or passing through the crystal in specific directions.

Explanation

In the dark, a Light Dependent Resistor (LDR) has a high resistance.

Explanation

• In atomic physics, the energy of an electron in an atom is quantized, meaning it can only take on specific discrete values.
• This is a fundamental principle of quantum mechanics, which states that energy is not continuous, but rather comes in small, discrete packets (quanta).
• The energy levels of electrons in an atom are determined by the solutions to the Schrödinger equation, and they are characterized by specific energy values, known as energy eigenvalues.
• These energy levels are quantized, meaning they can only take on specific values, and not any arbitrary value.

Explanation

• Radioactivity was discovered by Henri Becquerel, a French physicist, in 1896.
• He discovered this when he was studying uranium and noticed that it emitted radiation without an external source of energy.
  
• The term radioactivity was coined by Marie Curie, who, along with her husband, investigated this phenomenon.
• Rutherford, a British physicist, studied the properties of radioactive decay and named the particles alpha, beta and gamma.

Explanation

• Nights are cooler in the deserts than in the plains because Sand radiates heat more quickly than the earth.
• Because deserts have such little water vapor in the air, it makes it harder to trap heat or cold in a desert.
• At night, the sun no longer heats the desert and the heat from the day doesn't stay trapped.
• Because of this, some deserts can get cold at night, dropping to below 40F, which is definitely coat weather.

Explanation

• Gravitational potential is always negative, because it is defined as the work done per unit mass to bring an object from infinity to a given point in a gravitational field.
• Since the force of gravity is attractive, work must be done to move an object against the force of gravity, and this work is negative.