Explanation

Note According to KMU MDCAT answer key the correct answer is 'C'

A black body is an ideal radiator that radiates energy unequally at all wavelengths.

The intensity of radiation emitted by a black body varies with wavelength, following Planck's law.

The spectral distribution of this radiation is characterized by a peak wavelength that shifts depending on the temperature of the black body, which is described by Wien's displacement law.

Explanation

The wavelength of the radiation emitted when an electron in a hydrogen atom jumps from a higher orbit (n = 2) to a lower orbit (n = 1) can be calculated using the Rydberg formula:

Explanation

 in every instant of time, the wavelength associated with a freely falling body decreases.

This is because the de Broglie wavelength 

λ of a particle is inversely proportional to its momentum:

(𝜆=ℎ/𝑝 ).

where:

• $h$ is Planck's constant,
• $p$ is the momentum of the particle.

Explanation

In a reverse-biased PN junction, the reverse current is typically very small, usually in the range of microamperes (μA).

This current is primarily due to minority charge carriers.

Explanation

Lenz's law is consistent with the law of conservation of energy because it states that the induced current will always oppose the change that produced it.

Explanation

Lenz's law states that the direction of induced current in a closed loop is such that it opposes the change in magnetic flux that produced it.

This means that if the magnetic field through a loop increases, the induced current will flow in a direction that creates a magnetic field opposing that increase, and vice versa.

Explanation

Inductance ($L$) is primarily influenced by the following factors:

1. Number of Turns:

   The inductance increases with an increase in the number of turns in the coil. More turns create a stronger magnetic field, which enhances inductance.

2. Area of the Coil:

   The larger the cross-sectional area of the coil, the greater the inductance, as it can enclose more magnetic flux.

3. Length of the Coil:

   The inductance decreases with an increase in the length of the coil. A longer coil has a weaker magnetic field for a given current.

4. Core Material:

   The material around which the coil is wound (the core) affects inductance. Ferromagnetic materials increase inductance due to their higher permeability compared to air or non-magnetic materials.

Explanation

The induced electromotive force (emf) ($varepsilon$) in a moving conductor in a magnetic field can be calculated using the formula:

$$\epsilon =B\cdot L\cdot v$$

Where:

• $B$ is the magnetic field strength (in teslas),
• $L$ is the length of the conductor (in meters),
• $v$ is the velocity of the conductor (in meters per second).

Given:

• $B = 0.6 , text{T}$
• $L = 1 , text{m}$
• $v = 20 , text{m/s}$

Substituting the values into the formula:

$$\epsilon =0.6\text{T}\cdot 1\text{m}\cdot 20\text{m/s}=12\text{V}$$

Thus, the value of the induced emf is 12 V.

Explanation

Inside a solenoid, the magnetic field is:Uniform and directed along the axis of the solenoid.

 The field lines are parallel and evenly spaced, indicating a strong and consistent magnetic field inside the solenoid.

Explanation

The force $F$ acting on a charged particle moving in a magnetic field is given by the Lorentz force equation, which can be expressed as:

$$F = q(mathbf{v} times mathbf{B})$$

Where:

• $\mathrm{<font\; color="\#0000ff"><b>F\; is\; the\; force\; acting\; on\; the\; particle,</b></font>}$
• $q$ is the charge of the particle,
• $mathbf{v}$ is the velocity vector of the particle,
• $\mathbf{B}$ is the magnetic flux density (magnetic field strength) vector.

The cross product $\mathbf{v}\times \mathbf{B}$ indicates that the direction of the force is perpendicular to both the velocity and the magnetic field vectors. Thus, the correct expression for the force is $F=qv\times B$.