Explanation

There is no point in arguing.

Explanation

The phenomenon where light of suitable frequency falling on a metal surface ejects electrons is called the "photoelectric effect."

Explanation

The professor told her students about the project months in advance so that they would have "ample" time to complete their work.

Explanation

• For a vector field to be solenoidal, its divergence must be zero. The divergence of a vector field A = (x + 3y)i + (y - 2z)j + (x + mz)k is given by ∇ ⋅ A = ∂(x + 3y)/∂x + ∂(y - 2z)/∂y + ∂(x + mz)/∂z.
• Calculating the divergence:
  
• ∇ ⋅ A = 1 + 1 + m
• For the field to be solenoidal (∇ ⋅ A = 0), m must be -2.

Explanation

The statement "Highly polished mirror surfaces are very good radiators" is wrong.

Explanation

When the stress applied to the body is increased beyond the maximum value and then removed after some time, the body will "not be able to return to its original position." This situation is known as plastic deformation, where the body undergoes permanent deformation.

Explanation

The average translational kinetic energy of molecules is directly proportional to the temperature (in Kelvin).

Since the temperature is increased from 300 K to 750 K, the average translational kinetic energy will also increase by a factor of 750/300 = 2.5.

So, the average translational energy at 750 K will be:

6 x 10^-20 J x 2.5 = 1.5 x 10^-19 J

Explanation

When a dielectric sheet is placed between two charges, the electrostatic force between them will "decrease" because the presence of the dielectric reduces the electric field strength between the charges, thus decreasing the force experienced by them.

Explanation

To find the tension in the wire, we can use the formula:

T = μv^2

where T is the tension, μ is the linear density, and v is the wave speed.

First, we need to find the wave speed. We can do this by analyzing the wave equation:

Y = 0.021 sin (x + 30t)

The wave speed is given by the coefficient of t, which is 30 m/s.

Now we can plug in the values:

T = μv^2

= (1.3 x 10^-4 kg/m) x (30 m/s)^2

= 0.12 N

So the tension in the wire is 0.12 N.

Explanation

• A four-level laser is a type of laser that has four energy levels involved in the lasing process.
• The He-Ne laser (Helium-Neon laser) is a common example of a four-level laser.
• It works by exciting helium atoms, which then transfer their energy to neon atoms, causing them to emit laser light.