Which of the following is dimensionless quantity?

Explanation

Option A: Power is the rate at which energy is transferred. It is measured in watts, which are equivalent to joules per second. Option B: Frequency is the number of oscillations per unit time. It is measured in hertz, which are equivalent to cycles per second. Option C: The refractive index is a dimensionless quantity.A dimensionless quantity is a quantity that has no units. It is a pure number that is independent of any physical dimensions.The refractive index is a measure of how much a light beam bends when it passes from one medium to another. It is defined as the ratio of the speed of light in a vacuum to the speed of light in the medium.The refractive index has no units because it is a ratio of two quantities with the same units. The speed of light in a vacuum is a physical quantity with units of meters per second. The speed of light in a medium is also a physical quantity with units of meters per second. Option D: Impulse is the product of force and time. It is measured in newton-seconds.