Water has the highest specific heat of any known substance except hydrogen; that is, it requires more heat to raise the temperature of water a definite number of degrees than it does to raise the temperature of an equal amount of any other substance the same number of degrees. Practically this same thing can be stated in another way: Water in cooling gives out more heat than any other substance in cooling through the same number of degrees. For this reason water is used in foot warmers and in hot-water bags (General Science by Bertha Clark).

Correct Option: C

Water has the highest specific heat of any known substance except hydrogen; that is, it requires more heat to raise the temperature of water a definite number of degrees than it does to raise the temperature of an equal amount of any other substance the same number of degrees. Practically this same thing can be stated in another way: Water in cooling gives out more heat than any other substance in cooling through the same number of degrees. For this reason water is used in foot warmers and in hot-water bags (General Science by Bertha Clark).

When a fast-moving train passes a man standing on the platform at rest, the air between train and person also moves with greater speed. This rapidly moving air, by Bernoulli’s principle will have a lower pressure than the still air a few feet away. The still air, having higher pressure, and being behind the man standing close will tend to push him toward the train.

Correct Option: D

When a fast-moving train passes a man standing on the platform at rest, the air between train and person also moves with greater speed. This rapidly moving air, by Bernoulli’s principle will have a lower pressure than the still air a few feet away. The still air, having higher pressure, and being behind the man standing close will tend to push him toward the train.

Near-sightedness, also known as short-sightedness and myopia, is a condition of the eye where light focuses in front of, instead of on, the retina. This causes distant objects to be blurry while close objects appear normal. This defect can be corrected by wearing a concave (diverging) spectacle lens. The rays of light from a near object are diverged before entering the eye so that the cornea and eye lens can direct the focal point onto the retina.

Correct Option: B

Near-sightedness, also known as short-sightedness and myopia, is a condition of the eye where light focuses in front of, instead of on, the retina. This causes distant objects to be blurry while close objects appear normal. This defect can be corrected by wearing a concave (diverging) spectacle lens. The rays of light from a near object are diverged before entering the eye so that the cornea and eye lens can direct the focal point onto the retina.

Total internal reflection is the basic concept behind the optical fiber. Optical fiber employs the transmission of light down fibers of plastic or glass. Because the fibers are thin, light entering one is likely to strike the inside surface at an angle greater than the critical angle and, thus, be totally reflected. In fact, most fibers have a varying refractive index to allow more light to be guided along the fiber through total internal refraction.

Correct Option: C

Total internal reflection is the basic concept behind the optical fiber. Optical fiber employs the transmission of light down fibers of plastic or glass. Because the fibers are thin, light entering one is likely to strike the inside surface at an angle greater than the critical angle and, thus, be totally reflected. In fact, most fibers have a varying refractive index to allow more light to be guided along the fiber through total internal refraction.

Total internal reflection is responsible for glittering which occurs when the light from a denser media (liquid) tries to enter less dense media (air in bubble). This reflected light when captured by our eyes is seen as glittering.

Correct Option: C

Total internal reflection is responsible for glittering which occurs when the light from a denser media (liquid) tries to enter less dense media (air in bubble). This reflected light when captured by our eyes is seen as glittering.