The poles remains same whether the magnet is cut into two equal half or more and also pole strength remains same but magnetic moment reduces due to decrease in the length of the magnet. If a bar magnet is suspended by a thread, it will come to rest in a position close to the north-south direction. The end of the magnetic toward the north is called north pole (N-pole) of the magnet and the other end the south pole (S-pole). The poles of a magnet cannot be separated. If a bar magnet is broken into two parts, each part will be a complete magnet with the poles at its ends. No matter how many times a magnet is broken; each piece will contain N-pole at one end and S-pole at the other.

Correct Option: D

The poles remains same whether the magnet is cut into two equal half or more and also pole strength remains same but magnetic moment reduces due to decrease in the length of the magnet. If a bar magnet is suspended by a thread, it will come to rest in a position close to the north-south direction. The end of the magnetic toward the north is called north pole (N-pole) of the magnet and the other end the south pole (S-pole). The poles of a magnet cannot be separated. If a bar magnet is broken into two parts, each part will be a complete magnet with the poles at its ends. No matter how many times a magnet is broken; each piece will contain N-pole at one end and S-pole at the other.

Although bats use echolocation to detect their prey, and find their way around in the dark, the sounds which they emit are ‘ultrasonic’, which is another way of saying they are beyond the range of normal human hearing. Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is thus not separated from “normal” (audible) sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

Correct Option: D

Although bats use echolocation to detect their prey, and find their way around in the dark, the sounds which they emit are ‘ultrasonic’, which is another way of saying they are beyond the range of normal human hearing. Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is thus not separated from “normal” (audible) sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

Telescope and Microscope are two scientific instruments that serve their purposes differently. One of the main differences between a telescope and a microscope is that a telescope is used to view things that are far whereas a microscope is used to view things that are very near. Another important difference between telescope and microscope is that the focal length or the distance from the focal point to the lens is different in these two scientific instruments. As a result of this the focal point in the case of a telescope may be at a far off place. On the other hand the focal point in the case of a microscope is just a fraction of an inch off. The difference in the diameter of the lens used in the two instruments also matter a lot when it comes to the difference between them. The lens diameter or the aperture is much larger in a telescope. This is to ensure that the aperture allows tiny amount of natural light at the focal point .On the other hand only artificial illumination is used in a microscope.

Correct Option: D

Telescope and Microscope are two scientific instruments that serve their purposes differently. One of the main differences between a telescope and a microscope is that a telescope is used to view things that are far whereas a microscope is used to view things that are very near. Another important difference between telescope and microscope is that the focal length or the distance from the focal point to the lens is different in these two scientific instruments. As a result of this the focal point in the case of a telescope may be at a far off place. On the other hand the focal point in the case of a microscope is just a fraction of an inch off. The difference in the diameter of the lens used in the two instruments also matter a lot when it comes to the difference between them. The lens diameter or the aperture is much larger in a telescope. This is to ensure that the aperture allows tiny amount of natural light at the focal point .On the other hand only artificial illumination is used in a microscope.

In optics, Lambert’s cosine law says that the radiant intensity or luminous intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator is directly proportional to the cosine of the angle between the observer’s line of sight and the surface normal. The law is also known as the cosine emission law or Lambert’s emission law. A surface which obeys Lambert’s law is said to be Lambertian, and exhibits Lambertian reflectance. Such a surface has the same radiance when viewed from any angle. This means, for example, that to the human eye it has the same apparent brightness (or luminance).

Correct Option: D

In optics, Lambert’s cosine law says that the radiant intensity or luminous intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator is directly proportional to the cosine of the angle between the observer’s line of sight and the surface normal. The law is also known as the cosine emission law or Lambert’s emission law. A surface which obeys Lambert’s law is said to be Lambertian, and exhibits Lambertian reflectance. Such a surface has the same radiance when viewed from any angle. This means, for example, that to the human eye it has the same apparent brightness (or luminance).

The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 343.2 metres per second (1,126 ft/s). the speed of sound varies from substance to substance. Sound travels faster in liquids and nonporous solids than it does in air. It travels about 4.3 times as fast in water (1,484 m/s), and nearly 15 times as fast in iron (5,120 m/s), than in air at 20 degrees Celsius. Sound waves in solids are composed of compression waves (just as in gases and liquids), but also exhibit a different type of sound wave called a shear wave, which occurs only in solids.

Correct Option: A

The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 343.2 metres per second (1,126 ft/s). the speed of sound varies from substance to substance. Sound travels faster in liquids and nonporous solids than it does in air. It travels about 4.3 times as fast in water (1,484 m/s), and nearly 15 times as fast in iron (5,120 m/s), than in air at 20 degrees Celsius. Sound waves in solids are composed of compression waves (just as in gases and liquids), but also exhibit a different type of sound wave called a shear wave, which occurs only in solids.