Electric Forces/Fields
A positively charged plastic rod is brought near a neutral, electrically conductive metal soda can. What happens to the can?
The can will roll due to polarization
What is the equivalent resistance of 2 resistors, each with resistance of 3 Ω, connected in series?
6 Ω
A compass in a magnetic field will line up __________.
a. with the north pole pointing in the direction of the magnetic field
b. with the north pole pointing perpendicular to the magnetic field
c. with the north pole pointing opposite the direction of the magnetic field
a. with the north pole pointing in the direction of the magnetic field
What is the wavelength of an electromagnetic wave with frequency 10^(12) Hz?
3.0*10^(-4) m
True or false: A converging lens always produces an inverted real image.
False. If the object is closer to the lens than the focal point, this will produce a virtual upright image
Two particles, one with a charge of +3 μC and another with -2 μC, are separated by a distance of 3 meters. What is the approximate magnitude of the force between them? (k=9*10^9 N*m^2/C^2) (μC=10^(-6) C)
6*10^(-3) N
What is the equivalent resistance of 2 resistors, each with resistance of 3 Ω, connected in parallel?
1.5 Ω
The current in a conducting loop of wire is counter-clockwise. What is the direction of the magnetic field in the center of the wire?
out of the page/board
What is the energy (in eV) of an electromagnetic wave with frequency 10^(12) Hz?
4.1*10^(-3) eV
A person has a far point of 3m and a near point of 25 cm. Is this person near-sighted, far-sighted, or neither?
near-sighted
A +q charge and a -q charge are both located along the x-axis. Is there a point along the x-axis and in-between the two charges where the electric field is zero?
No. The electric fields due to each charge always point in the same direction as each other, so they can never add to zero
What property of objects is best measured by their capacitance?
a. the ability to conduct electric current
b. the ability to distort an external electrostatic field
c. the ability to store charge
c. the ability to store charge
An electron enters a magnetic field that points up with a velocity directed out of the page. What is the direction of the magnetic force on the electron?
To the right
True or false. Light of a particular frequency incident on a sodium surface results in photoelectrons. If I increase the intensity of light, I will get higher energy photoelectrons.
False - increasing the intensity increases the number of photoelectrons, but not their energy
A lens with focal length +15 cm is combined with a lens of focal length +10 cm. What is the focal length of the combination?
6 cm
A positive test charge is placed in a field. It is then replaced by a negative test charge. Does the direction of the electric field at that point change?
No, the direction of the force (F=qE) on the charge changes, but E at that point does not change.
When a light switch is turned on, the light comes on immediately because
a. the lightbulb may be old with low resistance. It would take longer if the bulb were new and had high resistance.
b. the electrons coming from the power source move through the initially empty wires very fast.
c.the electrons already in the wire are instantly "pushed" by a voltage difference.
c. the electrons already in the wire are instantly "pushed" by a voltage difference.
You hold a wire coil so that the plane of the coil is perpendicular to a magnetic field B. If the magnitude of B increases while its direction remains unchanged, how will the magnetic flux through the coil change?
The flux increases because the magnitude of B increases.
Compared to red light, blue light (smaller wavelength) incident on a double-slit will result in bright fringes that are spaced ______.
a. Closer together than red light
b. The same distance as red light
c. Further apart than red light
a. Closer together than red light
Consider a light ray that propagates from water (n1=1.33) to air (n2=1.0). If the incident ray strikes the interface at a nonzero angle, how does the angle of refraction compare to the angle of incidence?
a. θ2>θ1
b. θ2<θ1
c. θ2=θ1
a. θ2>θ1
If the electric field is zero at a certain point, must the electric potential also be zero there?
No, consider if you have 2 identical point charges separated by a distance. The electric field will be zero half-way between them, but the electric potential will be non-zero.
Two bulbs are connected in parallel. What happens to the brightness of one bulb if the other bulb is disconnected?
Nothing. It remains the same. The potential difference doesn't change, and R doesn't change, so the power doesn't change.
You hold a wire coil so that the plane of the coil is perpendicular to a magnetic field B that points into the page. If the magnitude of B decreases while its direction remains unchanged, what is the direction of the induced current in the wire?
Clockwise
In a vacuum, what is the difference between a radio wave and an X-ray?
Frequency/wavelength
An object is 35 cm from a lens with a 25 cm focal length. What is the image position?
s'=87.5 cm