A pulse of light with a speed of 3.0 x 108 m/s travels through a glass plate with a refractive index of 1.50 and a thickness of 0.9 cm. Calculate the time it takes for the light to pass through the pl

The thickness ($d$) is given as $0.9 \text{ cm}$.

$$d = 0.9 \text{ cm} \times \frac{1 \text{ m}}{100 \text{ cm}} = 0.009 \text{ m} = 9.0 \times 10^{-3} \text{ m}$$

The refractive index ($n$) is defined as the ratio of the speed of light in a vacuum ($c$) to the speed of light in the medium ($v$).

$$n = \frac{c}{v}$$

We are given $n = 1.50$ and $c = 3.0 \times 10^8 \text{ m/s}$.
Rearrange the formula to solve for $v$:

$$v = \frac{c}{n}$$ $$v = \frac{3.0 \times 10^8 \text{ m/s}}{1.50}$$ $$v = 2.0 \times 10^8 \text{ m/s}$$

Time is calculated by dividing the distance (thickness of the plate) by the speed.

$$t = \frac{d}{v}$$ $$t = \frac{9.0 \times 10^{-3} \text{ m}}{2.0 \times 10^8 \text{ m/s}}$$ $$t = \frac{9.0}{2.0} \times 10^{-3-8} \text{ s}$$ $$t = 4.5 \times 10^{-11} \text{ s}$$

Comparing this result with the given options:
A. $3.0 \times 10^{-10} \text{ s}$
B. $4.5 \times 10^{-11} \text{ s}$
C. $3.0 \times 10^{-11} \text{ s}$
D. $4.5 \times 10^{-10} \text{ s}$

The correct option is B.

The time taken is:

$$\boxed{\text{B. } 4.5 \times 10^{-11} \text{ s}}$$