Physics MCQs for NEET — Practice Questions with Answers

Diamagnetic materials do not have a permanent magnetic dipole moment; they are characterized by their ability to create an induced magnetic field in a direction opposite to an externally applied magnetic field. Therefore, the assertion is true (diamagnetic materials can exhibit magnetism in the presence of an external magnetic field), but the reason is false.

For paramagnetic materials, the magnetization increases as the temperature decreases. This is because the thermal agitation of the atoms reduces, allowing the magnetic dipoles to align more easily with the external magnetic field. Hence, the assertion is true, but the reason is false since magnetization does depend on temperature.

When two short magnets are placed on a cork such that their axes are perpendicular, the magnetic forces balance each other out, resulting in no net force or torque acting on the cork. This means the cork will have neither translational nor rotational motion. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

Both the assertion and reason are true. A current-carrying solenoid produces a magnetic field that is uniform and independent of its length and cross-sectional area. However, the reason does not explain why the magnetic field is independent of these factors.

The velocity of light is maximum in a vacuum. In a vacuum, light travels at its highest speed, which is approximately $3 imes 10^8 ext{ m/s}$. In other mediums like diamond, water, and glass, light slows down due to the higher refractive index.

When an object moves towards a plane mirror with a certain speed, the image formed in the mirror also moves towards the object with the same speed. Hence, if 'Bhautik' runs towards the mirror at $20 ext{ ms}^{-1}$, his image will also move towards him at $20 ext{ ms}^{-1}$.

According to the law of reflection, the angle of incidence is equal to the angle of reflection. Therefore, if a ray of light is incident at an angle of $30^ ext{circ}$, the angle of reflection will also be $30^ ext{circ}$. The angle between the normal and the reflected ray will be twice the angle of reflection, which is $60^ ext{circ}$.

$ no.of image = { 360 ^\circ \over \theta} = { 360 ^ \circ \over 0^\circ } = \infty $

To determine the angle between two plane mirrors to get a specific number of images, we can use the formula: \( n = \frac{360}{\theta} - 1 \), where \( n \) is the number of images formed and \( \theta \) is the angle between the mirrors. For five images, we set \( n = 5 \) and solve for \( \theta \): \( 5 = \frac{360}{\theta} - 1 \) \( 6 = \frac{360}{\theta} \) \( \theta = \frac{360}{6} = 60^\circ \). So the correct answer is 72 degrees.

When a glass rod is immersed in a liquid with the same refractive index, light passes through both materials without bending or reflecting at the boundary, making the rod virtually invisible. This is because there is no change in the speed of light and no refraction occurs at the interface.