Physics MCQs for NEET — Practice Questions with Answers

In an electromagnetic wave, the relationship between the electric field $(E)$ and the magnetic field $(B)$ is given by $E = cB$, where $c$ is the speed of light in a vacuum $(3 imes 10^8 ext{ m/s})$. Given $B = 3 imes 10^{-10} ext{ T}$, the amplitude of the associated electric field will be $E = 3 imes 10^8 ext{ m/s} imes 3 imes 10^{-10} ext{ T} = 9 imes 10^{-2} ext{ Vm}^{-1}$. Therefore, the correct option is $9 imes 10^{-2} ext{ Vm}^{-1}$.

In an electromagnetic wave, the electric field $( ext{E})$ and the magnetic field $( ext{B})$ are in phase and perpendicular to each other. This means that both fields reach their maximum and minimum values at the same points in space and time, and they are oriented at right angles to each other. This orthogonal relationship is a fundamental characteristic of electromagnetic waves.

The frequency $\nu$ of light can be calculated using the equation $\nu = \frac{c}{\lambda}$, where $c$ is the speed of light (approximately $3 \times 10^8$ m/s) and $\lambda$ is the wavelength. For a wavelength of $50000 \text{ Ã…}$, which is $50000 \times 10^{-10}$ meters, the frequency is $\nu = \frac{3 \times 10^8}{50000 \times 10^{-10}} = 6 \times 10^{14}$ Hz.

In an electromagnetic wave, the electric field ( \vec{E} ), magnetic field ( \vec{B} ), and the direction of wave propagation ( \vec{k} ) are all perpendicular to each other and follow the right-hand rule. If the magnetic field is along the +ve Z direction ( \vec{B} \uparrow \hat{z} ) and the wave is propagating along the +ve X direction ( \vec{k} \uparrow \hat{x} ), then the electric field ( \vec{E} ) must be along the +ve Y direction ( \vec{E} \uparrow \hat{y} ) to satisfy the right-hand rule.

The relationship between the amplitudes of the electric field ( E_0 ) and the magnetic field ( B_0 ) in an electromagnetic wave is given by E_0 = c B_0 , where c is the speed of light in a vacuum. This relationship comes from the fact that the magnitudes of the electric and magnetic fields are related by the speed of light: E = cB .

The velocity of light in vacuum, often denoted as 'c', is a fundamental constant and does not change with frequency, wavelength, or amplitude. It is approximately 3 x 10^8 meters per second and remains consistent regardless of these factors. Therefore, the correct answer is 'none of these'.