The specific resistance of a conducting wire depends upon

• length of the wire, area of cross-section of the wire, and material of the wire.

• length of the wire and area of cross-section of the wire but not on the material of the wire.

• the material of the wire only but neither on the length of the wire nor on the area of cross-section of the wire

• length of the wire only but neither on the area of cross-section of the wire nor on the material of the wire.

When X-rays are produced

• heat is generated at the target.

• heat is absorbed in the target.

• the temperature of the target remains constant

• brilliant light is seen at the target.

323.

Which one of the statements given below is not correct?

• A vertical plane passing through the axis of a freely suspended magnet is called the magnetic meridian

• A vertical plane passing through the axis of rotation of the Earth is called the geographical meridian.

• The degree to which the magnetic field can penetrate a medium is known as the relative permeability of the medium.

• The relative permeability is not a dimensionless quantity.

If an object is placed at the center of curvature of a concave mirror, the position of the image is

• at the principal focus

• between the principal focus and the center of curvature.

• beyond the center of curvature.

• beyond the center of curvature.

The radius of curvature of a plane mirror

• is zero

• is infinity

• can be anywhere between zero and infinity

• None of these.

A coin in a beaker filled with water appears raised. This phenomenon occurs because of the property of

• reflection of light.

• refraction of light

• total internal reflection of light

• interference of light

A ray of light falls on a transparent glass plate. A part of it is reflected and a part is refracted. The reflected and refracted rays can be perpendicular to each other for

• the angle of incidence equal to 90°.

• the angle of incidence equal to zero

• the angle of incidence equal to zero

• more than one angle of incidence

A particle oscillates in one dimension about the equilibrium position subject to a force F_x(a) that has an associated potential energy U(x). If k is the force constant, which one of the following relations is true?

• F_x(x) = -kx²

• F_x(x) = -kx

• $\mathrm{U}\left(\mathrm{x}\right) = \frac{1}{2}\mathrm{kx}$

• $\mathrm{U}\left(\mathrm{x}\right) = \frac{1}{2}{\mathrm{k}}^2\mathrm{x}$

When a body moves with simple harmonic motion, then the phase difference between the velocity and the acceleration is

• 0°

• 90°

• 180°

• 270°

A body is thrown vertically upwards and then falls back on the ground. Its potential energy is maximum

• on the ground

• at the maximum height

• during the return journey.

• both on the ground and at the maximum height