A car travels in a circular path of radius, r for one complete revolution. Its displacement at the end of the motion is

here are the solutions to the remaining questions:

22. A car travels in a circular path of radius, $r$ for one complete revolution. Its displacement at the end of the motion is
Displacement is the shortest distance between the initial and final positions. For one complete revolution, the car returns to its starting point. Therefore, the net displacement is zero.

• The correct option is A.

23. A monochromatic light loses 25% of its speed when it enters a transparent medium from air. Determine the refractive index of the medium.

Step 1: Define the speeds.
Let the speed of light in air be $c$.
The speed of light in the medium, $v$, is $c - 0.25c = 0.75c$.

Step 2: Use the formula for refractive index.
The refractive index $n$ is given by the ratio of the speed of light in air (or vacuum) to the speed of light in the medium.

$$n = \frac{\text{speed in air}}{\text{speed in medium}}$$ $$n = \frac{c}{0.75c}$$ $$n = \frac{1}{0.75}$$ $$n = 1.333...$$

• The correct option is B.

24. A metal has a work function of $1.82 \text{ eV}$. Calculate its threshold wavelength. [Planck's constant, $h = 6.63 \times 10^{-34} \text{ J s}$, speed of light, $c = 3.0 \times 10^8 \text{ m s}^{-1}$, $1 \text{ eV} = 1.602 \times 10^{-19} \text{ J}$]

Step 1: Convert the work function from electron volts (eV) to Joules (J).

$$\phi = 1.82 \text{ eV} \times (1.602 \times 10^{-19} \text{ J/eV})$$ $$\phi = 2.91564 \times 10^{-19} \text{ J}$$

Step 2: Use the formula relating work function, Planck's constant, speed of light, and threshold wavelength.

$$\phi = \frac{hc}{\lambda_0}$$

Rearrange to solve for $\lambda_0$:

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