JEE Advanced paper is considered to be one of the toughest entrance exams in India. Moreover, this Physics is considered the toughest subject because it is the most application-based. The student needs to get the basics right and then move on to mastering advanced concepts. Units and Measurements consist of nearly about 3-4 % of marks in the Physics section.

**Q1. Statement 1: ‘Light year’ and ‘Wavelength’ both measure distance**

Statement 2: Both have dimensions of time

Statement 2: Both have dimensions of time

Solution

(c)

Light year and wavelength both represent the distance, so both have dimensions of length not of time

(c)

Light year and wavelength both represent the distance, so both have dimensions of length not of time

**Q2. Statement 1: When we change the unit of measurement of a quantity, its numerical value changes**

**Statement 2: Smaller the unit of measurement smaller is its numerical value**

**Q3. Statement 1: Avogadro number is the number of atoms in one gram mole**

Statement 2: Avogadro number is a dimensionless constant

Statement 2: Avogadro number is a dimensionless constant

Solution

(c)

Avogadro number (N) represents the number of atoms in 1 gram mole of an element, i.e., it has the dimensions of mole

(c)

Avogadro number (N) represents the number of atoms in 1 gram mole of an element, i.e., it has the dimensions of mole

^{-1}

**Q4. Statement 1: Light year and wavelength have same dimensions**

Statement 2: Light year represents time while wavelength represents distance

Statement 2: Light year represents time while wavelength represents distance

Solution

(c)

Light year and wavelength both have same dimensions of length

(c)

Light year and wavelength both have same dimensions of length

**Q6. The time dependence of a physical quantity P is give by P = P**

_{0}e^{-Î±t2}, where Î± is a constant and t is time. Then constant Î± is**Q9. Given that T stands for time period and l stands for the length of simple pendulum. If g is the acceleration due to gravity, then which of the following statements about the relation T**

^{2}= (l/g) is correct?**Q10. The density of a solid ball is to be determined in an experiment. The diameter of the ball is measured with a screw gauge, whose pitch is 0.5 mm and there are 50 divisions on the circular scale. The reading on the main scale is 2.5 mm and that on the circular scale is 20 divisions. If the measured mass of the ball has a relative error of 2%, the relative percentage error in the density is**