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PHYS 1260 FINAL EXAM 2025/2026 SPRING ACTUAL
PREP QUESTIONS AND ANSWERS WITH
RATIONALES
An empty parallel plate capacitor is connected to the terminals of a 12.0V battery and charged up. While the battery is connected, a dielectric material is inserted between the plates. Which of the following choices describes how the capacitance, the charge, and the voltage across the capacitor are going to be affected?
a. the capacitance increases, the charge decreases, and the voltage remains the same
b. the capacitance increases, the charge increases, and the voltage remains the same
c. the capacitance decreases, the charge decreases, and the voltage increases
d. the capacitance remains the same, the charge decreases, the voltage decreases
e. the capacitance remains the same, the charge increases, the voltage remains the same
(RATIONALE: when a dielectric material is inserted, this means K in the capacitance equation increases, and since C and K are directly proportional, the capacitance increases. Therefore, due to the equation Q=CV, since C and Q are directly proportional, Q also increases. Also since the battery remains connected the entire time, the voltage is constant throughout the entire interaction.)
A plane mirror is 2.00 m tall. What is its focal length?
a) zero feet b) 1.00 m c) 2.00 m d) 4.00 m e) infinity
(Reasoning: If parallel rays fall on mirror, then after reflection they are still parallel and these rays appear to meet at infinity so the focal length of a plane mirror is infinity. )
A beam of light passes from air into water. Which is necessarily true?
a) The frequency is unchanged and the wavelength increases.
b) The frequency is unchanged and the wavelength decreases.
c) The wavelength is unchanged and the frequency decreases.
d) Both the wavelength and frequency increase.
e) Both the wavelength and frequency decrease.
(Reasoning: Light itself can behave as a particle or as a wave. Light is a type of electromagnetic wave that oscillates. The frequency at which the light shines on a surface will remain as the same intensity, however what changes is the wavelength traveling through different media depending on its index. (High --> Low = no shift in wavelength. Low --> High= a shift in wavelength occurring)
Complete the following statement: Fiber optics make use of a) polarization b) total internal reflection
between B, and the surface normal will either be 0, or 180 degrees which will make Sin(0) = 0 or Sin(180)=0.)
Three point-like charges of equal magnitudes are going to be placed at the corners of the rectangle shown in the figure. Which one of these is correct if the charge at corner (C) is positive, the charge at corner (D) is neutral, and the charge at corner A is negative? a. The total electric field at the center of the rectangle points toward the (C) corner b. The total electric field at the center of the rectangle points toward the (D) corner c. The total electric field at the center of the rectangle is zero d. The total electric field at the center of the rectangle points toward the (A) corner e. The total electric field at the center of the rectangle points toward the (B) corner
A parallel plate capacitor with plates of area (A) and plate separation (d) is charged so that the potential difference between its plates is (V). While the capacitor is still connected to the power source and its plate separation is decreased to d/2 , which statement is correct?
a. The capacitance is decreased to one-half its original value
b. The charge on the plates is decreased to one-half its original value
c. The charge on the plates is unchanged
d. The voltage between the plates is decreased to one-half of its original value
e. The charge on the plates is increased two times its original value
f. The capacitance is unchanged
g. The voltage between the plates is increased two times its original value
(RATIONALE: if the plate distance decreases, then this means that since the capacitance is indirectly proportional to the distance (d), that the capacitance will increase. Therefore, in the equation Q=CV where Q and C are directly proportional, that since C has increased, Q will also increase. The voltage on the other hand will remain constant since the capacitor remains connected to the power source the entire time.)
A parallel plate capacitor with plates of area (A) and plate separation (d) is charged so that the potential difference between its plates is (V). While the capacitor is still connected to the power source and its plate separation is increased three times the original distance (d) , which statement is correct?
a. The capacitance is decreased to one-third its original value
b. The voltage between the plates is decreased to one-third its original value
c. The charge on the plates is unchanged
d. The voltage between the plates is decreased to one-half of its original value
e. The charge on the plates is increased three times its original value
f. The capacitance is unchanged
g. The voltage between the plates is increased three times its original value
(RATIONALE: if the plate distance increases, the capacitance since it is inversely proportional to the plate distance (d) will decrease to one-third the original value. Therefore, due to the equation Q=CV, since Q and C are directly proportional, Q will also decrease to one-third its original value. The voltage since it remains connected the entire time will remain constant the entire time.)
What is the direction of the induced current in the circuit? a. None of these b. Clockwise c. Counterclockwise
At a particular moment in time and space, we measure an electromagnetic wave's electric and magnetic fields. We find the electric field (E) pointing North and the magnetic field (B) pointing Up. What is the direction of the wave propagation?
a. east
b. up
c. south
d. west
e. north
f. down
e. north
At a particular moment in time and space, we measure an electromagnetic wave's electric and magnetic fields. We find the electric field (E) pointing west and the magnetic field (B) pointing up. What is the direction of the wave propagation?
a. east
b. up
c. south
d. west
e. north
f. down
Which one of the following statements is true concerning the magnitude of the electric field at a point in space?
a. It is a measure of the total charge on the object. b. It is a measure of the electric force on any charged object. c. It is a measure of the ratio of the charge on an object to its mass. d. It is a measure of the electric force per unit mass on a test charge. e. It is a measure of the electric force per unit charge on a test charge.
b. the sign of the charge causing the field.
(reasoning: The magnetic force Fmag is always perpendicular to the velocity The magnetic force Fmag F mag is always perpendicular to the velocity v v of the charged particle. Therefore, the magnetic force does not change the speed of the particle (magnitude of velocity). It only changes the direction of the velocity, making the particle move in a circular or helical path. of the charged particle. Therefore, the magnetic force does not change the speed of the particle (magnitude of velocity). It only changes the direction of the velocity, making the particle move in a circular or helical path.)
Complete the following statement: The magnitude of the electric field at a point in space does not depend upon...
a. the distance from the charge causing the field.
b. the sign of the charge causing the field.
c. the magnitude of the charge causing the field.
d. the force that a unit positive charge will experience at that point.
e. the force that a unit negative charge will experience at that point.
a. The magnetic force does no work on the particle b. The magnetic force increases the speed of the particle. c. The magnetic force changes the velocity of the particle. d. The magnetic force can act only on a particle in motion. e. The magnetic force does not change the kinetic energy of the particle.
( Reasoning: only a force enacted on an object can increase the speed it travels at. think of it like pushing a toy car, the harder you push it, the faster it will go.)
The figure shows a uniform magnetic field that is normal to the plane of a conducting loop with resistance R. Which one of the following changes will cause an induced current to flow through the resistor?
a. decreasing the area of the loop
b. decreasing the magnitude of the magnetic field
c. increasing the magnitude of the magnetic field
d. rotating the loop through 90° about an axis in the plane of the paper
e. all of the above
Which one of the following phenomena would be observed if the wavelength of light were increased in a single-slit diffraction?
a) The fringes would be brighter.
b) More bright fringes would appear on the screen.
c) The distance between dark fringes would decrease.
d) Single-slit diffraction effects would become non-negligible.
e) The angular separation between bright fringes would increase.
( Reasoning: The amount of light bending increases the wavelength. As the wavelength increases the separation between the bright fringes on the screen will increase. This demonstrates a wavelength, if you are to increase the wavelength, the longer it would take to get to its next peak (think of the peak as like a dark fringe) )
In a Young's double slit experiment, which one of the following phenomena would be observed if the separation between the two slits were increased?
a) the angular separation between the dark fringes would decrease. b) The fringes would become brighter. c) The central bright fringe would change location. d) the distance between the dark fringes would increase. e) the distance between the bright fringes would increase.
In a double-slit experiment, which of the following phenomena would be observed if the distance between the slits were decreased?
a. The central bright fringe would change position b. The fringes would become brighter c. The distance between dark fringes would decrease d. The angular separation between the dark fringes would decrease e. The distance between bright fringes would increase
convex, real, concave, virtual
In a converging lens, when the ____________ is placed outside of the focal point, the image that is created is real, and ____________. You can draw two focal points for a converging lens, the one on the _______ side as the object can be used as a guide to indicate if the object is outside of the focal point or within the focal point which will help to determine the properties of the ___________. The other focal point is known as the _______ focal point since it forms where the incident rays converge, which can help determine where the image forms.
object, inverted, same, image, real
Converging lens (convex) focal point understanding:
If the object is between 2F and F, it will be ___________, If the object is exactly at 2F then the image will be the ________ ______ as the object, while if the object is outside of the 2F and F, the image will be ______________
magnified, same size, diminished
An Object placed outside of the focal point for a converging lens will be: _____________, _____________ and _____________
real, enlarged, inverted
An object placed within the focal point for a converging lens will be: ____________, __________, and ___________
virtual, enlarged, upright
In a Diverging lens, again you can create two focal points, one which is placed on the same side as the object, and the second which will be on the opposite side of the lens. Again the focal point placed on the same side of the object helps you to determine if the object is positioned ______________ or __________ to the focal point. When incident rays that are parallel to the principal axis pass by the object and hit the diverging lens, the rays once they pass through will ________________ away from the focal point on the opposite side. You can trace those rays backward to the focal point on the same side as the object, and this will reveal an __________.
Diverging lenses always create ____________, _____________, and ____________ images.
outside, inside, object, diverge, image, virtual, diminished, upright
A sculpture is placed at a distance (y) from a mirror whose radius of curvature is (r). In order to see the image of the sculpture upright and enlarged, the mirror...
a. must be concave, with y> r/2. b. must be convex, with y<r. c. must be convex, with y>r. d. must be concave, with y<r/2. e. must be concave, with y=r.
(Reasoning: concave mirrors only produce virtual, upright, and enlarged images when the object is placed within the focal (r/2) of the mirror.)
Consider a real object and a single converging (convex) or diverging (concave) lens, Which of the following statements is not correct?
a. Either one of the lenses produce virtual images b. The image produced by the converging lens can be real or virtual
Snell's law only applies to a surface that
Is non-metallic
If light were to travel from a region of higher density to a region of lower density, what would you observe in the lights behavior?
It would bend away from the normal
If the magnification is less than one and positive
The image is smaller and upright
If you were told that light struck an interface made of glass. What would you know?
The refractive measurements of the glass
In a convergence lenses, the image will have one of the following features...
It will be upside down and on the opposite side of the lenses
In a divergence lens, the calculated image is negative. This negative answer tells you....
The image is not real
In the right hand rule the thumb will tell you the direction of the..
Moving charges
Light work comes in two forms. Once the charges go in motion, which form will be produced?
The magnetic field
When using a polarizer that is perpendicular to one of the two fields, how much energy remains?
Only half
If light had a refractive angle that was known... what do you also know?
The incoming angle
Reflection
Angle equal to incoming ray of light or incidence Ray
Scattering
Wavelength
Huygens principle(diffraction)
The connection of the Ray and wave viewpoint
Diffraction
a change in the direction of a wave when the wave finds an obstacle or an edge, such as an opening
Rainbow
Main arc, Alexander's band, secondary arc : combines dispersion refraction and reflection
Frequency
Will not change
Diverging lenses(negative lens)
Thin at center and thick at ends. They will always produce a virtual image that is SMALL and UPRIGHT. Nearsighted people use these lens
Convergence lens(positive lens)
Are thicker at the center and thin at the ends. Farsighted people use these lens. Image will be real and inverted. Image is enlarged.
If object falls between the focal point and lens
Image is virtual and diverginfb
If the focal length is + then,
It is a converging lens
If the focal point is - then,
It is a diverging lens
If object distance(d0,s0) is +then,
