Answer:
(a) 313nm
(b) 250nm
(c) 301nm
Explanation:
This problem involves the concept of thin-film interference. The scientist observes constructive interference. In this case m = 1.
(a) To find the thickness of the oil at that spot we need to first calculate the wavelength in the oil.
λ = λo/n = 750/ 1.20 = 625nm
λ = wavelength in the material of interest into which light is entering (the oil)
λo = wavelength in the material from which light is coming in or entering.
n = refractive index of the material into which the light is entering.
Light travels from air into the oil. So the refractive index used above is that of the oil and not air.
The formula relating the thickness t to the wavelength is 2t = mλ
m = 1 so,
2t = λ = 625nm
t = 625/2 = 313nm
(b) Supposing the refractive index of the water is now n = 1.50
The wavelength in the oil λ = 750/1.50 = 500nm
The thickness t = λ/2 = 500/2 = 250nm
(c) If the oil has a thickness of 200nm then the wavelength λ = 2t = 2 ×200nm = 400nm
The wavelength in the oil is 400nm. In order to find the wavelength in water we set this wavelength to λo = 400nm. So the wavelength in water seen by the diver is given by the formula
λ = λo/n
n for water is 1.33
λ = 400/1.33 = 300.8nm ≈ 301nm.
Answer: fourth option 1.2 × 10³ joules
Explanation:
1) kinetic energy is calculated as the half of the product of the mass times the square of the speed:
=> KE = (1/2) m × (v)²
2) you know the mass after the collision and the speed so you have all the data fo find the numerical value of the expression for KE:
m = m1 + m2 = 200 kg + 250 kg = 450 kg
KE = (1/2) × 450 kg × (2.3 m/s)² = 1,190.25 joules ≈ 1200 joules = 1.2 × 10³ joules, which is the last option of the list.
This question is incomplete, the complete question is;
Two plane mirrors intersect at right angles. A laser beam strikes the first of them at a point 11.5 cm from their point of intersection, as shown in the figure.
For what angle of incidence at the first mirror will this ray strike the midpoint of the second mirror (which is 28.0 cmcm long) after reflecting from the first mirror
Answer: angle of incidence is 39.4°
Explanation:
Given that;
two plain mirrors intersect at right angle (90°)
distance d = 11.5 cm
S = 28.0 cm
Now the angle that the reflection ray males with first the mirror equal theta (∅)
so
tan∅ = (S/2) / d
tan∅ = (28/2) / 11.5
tan∅ = 14 / 11.5
tan∅ = 1.2173
∅ = tan⁻¹ (1.2173)
∅ = 50.6°
so angle of incidence = 90° - ∅
= 90° - 50.6°
= 39.4°
Therefore angle of incidence is 39.4°
There is a force of gravity acting downward on the object,
and no force acting upward on it.
Since the vertical forces on it are unbalanced, it accelerates
in the direction of the net vertical force, which is downward.
A second important difference between comets coming from the Kuiper Belt and from the Oort cloud is represented by their different characteristic periods.
In fact, short period comets are thought to generate in the Kuiper belt and have rather predictable orbits with short periods (up to 200 years). There are two major families of short period comets: the Jupiter family with periods of less than 20 years and the Halley family with periods form 20 to 200 years. That's short