A Level Physics Practice Exam

What is the distance between the centers of two adjacent slits on a diffraction grating that has 300 slits per mm?

1. 3.0 x 10^-3 m

2. 3.3 x 10^-3 m

3. 5.0 x 10^-3 m

4. 1.0 x 10^-3 m

The correct answer is: 3.3 x 10^-3 m

To find the distance between the centers of two adjacent slits on a diffraction grating, you can use the information that there are 300 slits per mm. The first step is to understand that "slits per mm" indicates how many slits fit into one millimeter. Since there are 300 slits in 1 mm, the distance between two adjacent slits, which is the same as the width of one slit plus the gap to the next slit, can be calculated by taking the reciprocal of the number of slits per unit length. 1 mm is equivalent to 1,000 micrometers or 1,000,000 micrometers. Therefore, if there are 300 slits in 1 mm, the distance \( d \) between adjacent slits is calculated as: \[ d = \frac{1 \text{ mm}}{300} \] Converting mm to meters for final clarity: \[ d = \frac{1 \times 10^{-3} \text{ m}}{300} = \frac{1 \times 10^{-3}}{300} = 3.33 \times 10^{-6} \text{ m} \] This result equ