1) Which one of the following statement about scientific hypothesis is FALSE
b) A scientific hypothesis is an explanation for natural phenomenon.
c)In order to be useful, a scientific hypothesis must be testable in a. way that is replicable by other scientist
d)The previously known outcome of an observation or experienment can be used as solid proof that a newly created scientific hypothesis is absolutely true

2)How does the path of the Sun change with the seasons for an observer located near the North Pole?
b)The maximum altitude of the is higher in the sky during summer
c)The maximum altitude of the inn the sky increases in the autumn
d)The maximum altitude of the in the sky decreases in the spring

4)IN the Northern Hemisphere, an observer at a higher latitude sees more circumpolar stars compared to an observer at a lower latitude, this is because?
a)The North Celestial pole is higher in the sky for an observer at a higher latitude
b)The north celestial pole is lower in the sky for an observer at a higher latitude
c) the zenith is her in the sky for an observer at a higher latitude

5)Choose the correct statement about precession of the Earth's axis?
a) Precession of the Earth's axis of rotation is caused by changes in the shape of the Earth's orbit due only to the gravitational pull of the Sun.
b)After thousands of years, the Earth's spin axis will have drifted away from Polaris and will point in a different direction.
d)Precession of Earth;s rotational axis does not affect the position of Earth's pole star

6)The worse of Earth's gravity pulls down on a snowfaleka s it floats gently toward the ground. What is the "equal and opposite force" during this interaction, according to Newton;s third law?
a)The force of the air pushing up on the snowflake
b)The force of the snowflake gravity pulling up on the Earth
d) there is no equal and opposite force in this case

1. Suppose a certain wavelength of light falls on a diffraction grating and creates an interference pattern.

   1. What happens to the interference pattern if the same light falls on a grating that has more lines per centimeter?

   2. What happens to the interference pattern if a longer-wavelength light falls on the same grating?

   3. Suppose a feather appears green but has no green pigment. Explain in terms of diffraction.

   4. Why is the index of refraction always greater than or equal to 1?

   5. Draw how light changes direction (toward or away from the perpendicular) in the following situations:

   6. goes from air to water?

   7. goes from water to glass?

   8. goes from glass to air?

   9. Why does the wavelength of light decrease when it passes from vacuum into a medium?

   10. Describe the types of images the following “devices” can create, and where the object needs to be located in relation to the “device” for that type of image to occur. Be clear in discussing all cases.

   11. a convex mirror

   12. a concave mirror

   13. a convex lens

   14. a concave lens

a) Calculate, in units ofℏ, the magnitude of the maximum total (orbital+spin) angular momentum for an electron in a hydrogen atom for states with a principal quantum number of 5.

b) An electron initially in a 4p state decays to a lower energy state. Which energy state is forbidden? (pick one): 1s, 2s, 3d, or 2p? Why?

c) What is the total number of electrons that can occupy a subshell for a given amount of orbital angular momentum l? Write an expression in terms of l.

A fast-moving electron beam strikes a metal target and produces a sharp peak in emission at one frequency as well as the bremsstrahlung continuum emission.

a) What causes this peak in X-ray spectrum? Explain what happens to the electrons in the metal atom.

b) Can a hydrogen atom emit x-rays? Explain why or why not (be quantitative about photon energy).

In the diffraction lab, we will use a laser which has wavelength is 650 nm and aim it at the hair until a clear diffraction pattern is visible on the screen or wall.

1. Does fine or coarse hair result in a greater distance between fringes in the resultant diffraction pattern? Explain the reasoning for your response.

2. Explain why laser light is used for this lab activity.

3. Differentiate between interference and diffraction and provide a common example of each from your home, work, or school experiences.

A plane leaves the airport in Galisteo and flies 170km at 68.0 degrees east of north and then changes direction to fly 230 km at 48.0 degrees south of east, and then changes direction to fly 120 mi west, after which it makes an immediate emergency landing in a pasture. When the airport sends out a rescue crew, in which direction and how far should this crew fly to go directly to the plane?

Intrinsic carrier density of Ge is 1.7x1019 /m3
. It is doped with a pentavalent impurity of 1ppm. Assuming all impurity atoms are ionized, calculate the factor by which the majority concentration is more than the intrinsic carrier concentration.

A boron nitride (BN) film was deposited using a reactive radiofrequency magnetron sputtering substrate. The deposition rate was 200nm/hr. The XPS compositional analysis showed that boron-to-nitrogen atomic ratio was 1/1 while the FTIR analysis indicated that the ratio of cubic phase (cBN) to hexagonal (hBN) phase was 55 % t0 45 %. What was the ion-to-deposition flux ratio when the ion current density was 4 mA/cm2? (Deposition area: 1/cm2; cBN mass density: ρcBN =3.48 g/cm3, Boron: Ma = 10.811 g/mol; Nitrogen: Ma = 14.0067 g/mol; hBN mass density: ρhBN =2.25 g/cm3; cBN mass density: ρcBN =3.48 g/cm3)

Describe in detail the Hertzsprung Russell (HR) diagram. Include the information contained on the vertical and horizontal axles, as well as the location of a Red Super Giant, a high mass main sequence star, a Sun like star, and low mass main sequence star, and a white dwarf star.

How do stars evolve on the HR diagram? Chose and describe of an object along one of the following:

• The Hayashi track
• The Henyey track
• The Asymptotic Giant Branch

this is for AST 1002

An atom in an l=1 state emits a photon of wavelength 500.000 nm as it drops to an l=0 state when there is no external magnetic field.

a)Calculate the Zeeman effect splitting (in electron volts) between adjacent energy levels when this atom is placed in an external3.00-Tmagnetic field. (eV)

b) List the wavelengths of the 3 spectral lines that could be observed with a high-resolution spectrographas a result of the interaction of the atom with the B field. Hint: you may use |dE/E| = |dλ/λ|.Find λ1λ2λ3 in nm. Use 6 sig figs for each.

c) Draw an energy diagram showing the 3 different transitions responsible for λ1λ2 and λ

Problem 1. A particle is orbiting a star of mass M in a circular orbit. (a, 2 POINTS) Find the equation that provides the orbital speed at a given distance r from the center of the star. (b, 1 POINT) From the result at (a), calculate at what distance rS the particle should be from the center of the star for its orbital speed to be equal to the speed of light, c (in this case, the particle would be a photon). (c, 1 POINT) Calculate that distance, rS for a star of mass equal to M = 10M, where the mass of the Sun is M = 1.99 × 1030 kg and c = 2.997925 × 105 km/s. (d, 4 POINTS) If the particle is a star orbiting the Galaxy, find and plot the function that describes the speed of the star as a function of its distance from the center of the Galaxy, r. You must calculate this in two cases, if the star is inside or outside the Galaxy. Assume the Galaxy is a homogeneous sphere of maximum radius RGalaxy and density ρ0. (e, 2 POINTS) If the Sun is inside the Galaxy, its orbital speed is 220 km/s and its distance from the center is 25 × 1019 m, what is the mass in kilograms of the part of the Galaxy contained within the orbit of the Sun?

Light emitting diodes, lasers

1. Describe what physical property of a semiconductor will deem it good or bad for use in an LED.

2. Describe general operation and configuration of an LED, what determines the emission wavelength (color).

3. Describe the role of defects in emission in terms of an energy band diagram.

4. Define heterojunction, homojunction, epitaxy

5. Describe why lattice matching is important (broadly)

6. Describe why LED emission does not occur at a single wavelength, and how you expect this to change with temperature

7. Describe the general operation of a laser and the concept of population inversion

8. Describe why the linewidth of a laser is more narrow than that of a light emitting diode

1. Two devices that can be used to breakdown a spectrum into its components are the a. telescope and microscope

b. telescope and prism

c. diffraction grating and microscope d. prism and diffraction grating

2. The color cyan is made up of what two primary colors?

a. green and blue                   b. green and red

c. red and blue                       d. none of the above

3.

Using the chart above, what color/wavelength could the brain perceive if the eye sends the following code to the brain via the optic nerve?

Type I = 0      Type II = 14 Type III = 7

a. 500 nm                   b. 525 nm

c. 550 nm                   d. 575 nm

4. Which of the following colors is scattered the least in the atmosphere?

a. red

b. green c. blue

d. yellow

5.

The emission spectrum shown above could be for light produced by

a. an incandescent light bulb

b. the sun

c. hydrogen gas

d. a green LED

6. White objects appear white because they…

a. reflect all wavelengths of visible light equally

b. scatter light of all wavelengths in a 360 degree direction c. exhibit total internal reflection

d. absorb all wavelengths of visible light equally

7. Lemons appear yellow because they…

a. absorb red and green and scatter blue light.

b. absorb blue and scatter red and green light.

c. absorb blue and scatter yellow light.

d. absorb yellow and scatter red and green light.

8. A nearsighted person’s eyes

a) refract light too little and focus images of distant objects in front of the retina.

b) refract light too much and focus images of distant objects behind the retina.

c) refract light too much and focus images of distant objects in front of the retina.

d) have pupils that are too small.

9. At present, a compact disc can only hold about 1 hour of music. This limit is due in large part to the fact that

a) a compact disc cannot turn faster than about 5 turns per second without experiencing a net torque of zero.

b) light cannot be focused to a spot that is significantly smaller than its wavelength.

c) the ridges in the aluminum layer of the compact disc cannot experience destructive interference unless they have a wavelength that is almost equal to the distance between them.

d) a compact disc cannot turn slower than about 5 turns per second without experiencing a net torque of zero.

10. On average, how much sunlight is typically available on the ground of the Earth?

a) 171 Watts per sq. meter.

b) 1368 Watts per sq. meter

c) 174 Petawatts per sq. meter.

d) 11 Watts per sq. meter

PN Junctions and breakdown

1. Draw and interpret energy band diagram for pn junction in equilibrium, forward, and reverse bias

2. Describe what physically happens (And why) when you put n-Si in contact with p-Si (e.g., junction formation)

3. Calculate Vo, W, Wn, Wp

4. Describe how/why current flows in forward and reverse bias.

5. Utilize law of junction to calculate the minority carrier concentration just outside the depletion layer

6. Quantify the forward and reverse bias current in a p-n junction given appropriate information

7. Describe the meaning of the diode ideality factor for values of 1 and 2 and in between

8. Describe what constitutes “short diode” conditions

9. Calculate the depletion layer capacitance given sufficient information

10. Identify the two mechanisms that allow for reverse bias breakdown of a diode.

11. Describe what occurs during Zener tunneling and avalanche and the conditions that this will occur