Physical Science Final Exam Review
Two point charges each with 0.14C of charge are 6.0×10−2m apart. Knowing that k is 9 × 109 N ⋅ m2 /C2 (the proportionality constant for Coulomb's law), find the force between the charges.
(9 • 10^9 • q^2) / d^2 = 4.9 x 10^10 N
How much current is in a 60-W light bulb connected to 120 V?
0.5 A
A weight suspended from a spring bobs up and down one complete cycle every 2 s. Its frequency is
0.5 Hz.
Use Ohm's law (I = V /R) and find the equivalent resistance of a parallel circuit with n branches.
1/Req = 1/R1 + 1/R2 + 1/R3........ + 1/Rn
The total charge that an automobile battery can supply without being recharged is given in ampere-hours. A typical 12-V battery has a rating of 60 ampere-hours (60 A for 1 h, 30 A for 2 h, and so on). Suppose that you forget to turn off the headlights in your parked automobile. If each of the two headlights draws 3 A, find the time that your battery will go dead.
10 h
A pair of 60-W and 100-W incandescent lamps are intended for 120-V operation. Which lamp draws more current?
100 W lamp
An incandescent lightbulb with an operating resistance of 95Ω is labeled "150 W." Is this bulb designed for use in a 120-V circuit or a 220-V circuit?
120 V
A certain bulb with a resistance of 95 ohms and labeled "150 W" is designated for use in a
120 V circuit
Calculate the power of a hair dryer that operates on 130V and draws a current of 11A .
1400 W
As a train of water waves goes by, a piece of cork floating on the water bobs up and down one complete cycle each second. The waves are 2 m long. What is the speed of the wave?
2 m/s
A pair of 1-ohm resistors connected in series has a combined resistance of
2 ohms
When a battery does 24 J of work on 10 C of charge, the voltage it supplies is
2.4 V
The electric power of a lamp that carries 2 A at 120 V is
240 W
A length of wire has resistance R. The same wire twice as long has resistance
2R
The electric force on a 2-C charge is 60 N. How great is the electric field at the charge location?
30 N/C
If 6 V were impressed across the circuit, consisting of two lamps connected in series, and the voltage across the first lamp were 2 V, what would be the voltage across the second lamp?
4 V
An electric heater is rated at 300 W when used in a 110-V circuit. The safety fuse in the circuit can accommodate 15 A of current. How many heaters can be safely operated in the circuit?
5
Consider a circuit with a main wire that branches into two other wires. If the current is 10 A in the main wire and 4 A in one of the branches, how much current is in the other branch?
6 A
How much energy is given to each coulomb of charge passing through a 6-V battery?
6 J
A coulomb of charge passing through a 6-V battery supplies
6 joules
A 60 vibration per second wave travels 30 m in 1 s. Its frequency is
60 Hz and it travels at 30 m/s.
A pair of 60-W and 100-W incandescent lamps are intended for 120-V operation. Which lamp has a larger resistance?
60 W lamp
What is the power rating of a device that draws 0.8 A when connected to 120 V?
96 W
Explain why middle C (or any other tone) has a longer wavelength in water than in air.
By the time the vibration completes one cycle, the wave travels farther in water than in air, so the wavelength, which is the distance the wave travels in one period, is longer in water.
Suppose you operate a 50-W lamp continuously for 1 week when the power utility rate is 8¢/kWh.
C = (P/1000) • 168 • 0.08 = 0.67
A droplet of ink in an industrial ink-jet printer carries a charge of 1.7 × 10^−10 C and is deflected onto paper by a force of 2.2 × 10^−4 N
E = (F/q) • 10^6 = 1.3 x 10^6 N/C
The unit of resistance is named after
Georg Simon Ohm
When you touch your fingers (resistance 1000 Ω) to the terminals of a 6.0-V battery, find the current moving through your fingers.
I = V/1000 = 6 x 10^-3 A
As in the video, we apply a charge +Q to the half-shell that carries the electroscope. This time, we also apply a charge -Q to the other half-shell. When we bring the two halves together, we observe that the electroscope discharges, just as in the video. What does the electroscope needle do when you separate the two half-shells again?
It does not deflect at all
A length of wire has resistance R. Two of these same-length wires braided together have a resistance
R/2
How do the masses of electrons compare with the masses of protons?
The masses of electrons are much less than the masses of protons.
Sound waves can interfere with one another so that no sound is produced.
True
A sustained flow of electric charge requires
a potential difference
The unit of electric charge, the coulomb, is the charge on
a specific large number of electrons.
Which has greater resistance: a thick wire or a thin wire of the same length?
a thin wire
Sound waves cannot travel in
a vacuum
A standing wave occurs when
a wave reflects upon itself.
Does the generator at a power station produce dc or ac?
ac
Wave interference occurs for
all of the above (water, sound, and light waves)
A sonic boom can NOT be produced by
an aircraft flying slower than the speed of sound.
What kind of charge does an object acquire when electrons are stripped from it?
an object is left with a positive charge
The vibrations of a transverse wave move in a direction
at right angles to the direction of wave travel.
The source of electrons lighting an incandescent ac light bulb is
atoms in the light bulb filament
For light, a red shift indicates the light source moves
away from you.
A sustained electric current can be achieved with a
both (generator & battery)
The electric force between charges is strongest when the charges are
close together
When both voltage and resistance are doubled?
current doesn't change
What is the effect on current through a circuit of steady resistance when the voltage is doubled?
current is doubled
Does a battery produce dc or ac?
dc
The fundamental force underlying all chemical reactions is
electrical
A positive ion has a deficiency of
electrons
The electric current in a copper wire is normally composed of
electrons
The number of protons in the nucleus of an electrically neutral atom is equal to the number of
electrons that surround the nucleus.
What moves from place to place in wave motion is
energy
A shock wave is produced when the speed of an object
exceeds the speed of sound in air.
Does current flow across a circuit or is it impressed across a circuit?
flow across a circuit
High pitched sound has a high
frequency.
The pitch of a musical sound depends on the sound wave's
frequency.
While at a concert, a wind blows directly from the orchestra toward you. The wavelength of the sound you hear is
increased
A positive and a negative charge near each other are released. As they move, the force on each particle
increases
If you double the frequency of a vibrating object, its period
is half
If you were so foolish as to play your keyboard instrument underwater, where the speed of sound is 1500 m/s, find the wavelength of the middle-C tone in water would. Assume that it's frequency is 256.0 Hz.
lambda = 5.86 m
Compared to the resistance of two resistors connected in series, the same two resistors connected in parallel have
less resistance
When two lamps are connected in parallel to a battery, the electric resistance that the battery senses is
less than the resistance of either lamp.
Which is more dangerous, touching a faulty 120-V light fixture, or a Van de Graaff generator charged to 100,000 V?
light fixture
When a pendulum clock at sea level is placed at the top of a high mountain, it will
lose time.
A wave barrier is produced in water when the speed of an object
matches the speed of waves in water.
A node is a position of
minimum amplitude
Compared to a single lamp connected to a battery, two lamps connected in parallel to the same battery will draw
more current
When two lamps are connected in series to a battery, the electric resistance that the battery senses is
more than the resistance of either lamp.
A rubber rod rubbed with fur becomes
negatively charged
Our ears are best at hearing
neither (NOT ultrasonic sound OR infrasonic sound)
To say that electric charge is conserved means that no case has ever been found where
net charge has been created or destroyed.
During a single period, the distance traveled by a wave is
one wavelength
To say that one wave is out of phase with another is to say that the waves are
out of step.
Electric field lines about a point charge extend
outward when the charge is positive.
The headlights, radio, and defroster fan in an automobile are connected in
parallel
When we consider the time taken for a pendulum to swing to and fro we're talking about the pendulum's
period.
If you strip electrons from an atom, the atom becomes a
positive ion
A negatively charged rod is brought near a metal can that rests on a wood table. You touch the opposite side of the can momentarily with your finger. The can then becomes
positively charged
What is the relationship among electric power, current, and voltage?
power = current × voltage
Which doesn't belong to the same family?
radio waves.
One main difference between gravitational and electric forces is that electric forces
repel or attract
A difference between electric and gravitational forces is that electric forces include
repulsive interactions
Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is greater in the lamp with the
same in each
You dip your finger repeatedly into water and make waves. If you dip your finger more frequently, the wavelength of the waves
shortens
When the handle of a tuning fork is held solidly against a table, the sound becomes louder and the time the fork keeps vibrating becomes
shorter.
Reverberation is a phenomenon you would likely to hear if you sing in the
shower
The explanation for all types of refraction involves a change in
speed.
A compression is a squash and a rarefaction is a
stretch.
The source of electrons in an ordinary electric circuit is
the electric conductor itself.
When a person experiences an electric shock, the origin of the electrons comprising the shock is
the person's own body.
Does electric charge flow across a circuit or through a circuit?
through a circuit
If you plug an electric toaster rated at 110-V into a 220-V outlet, current in the toaster will be about
twice what it should be
A 2.0-m-long wave oscillates 1.3 times each second. Find the speed of the wave.
v = T • L = 2.6 m/s
Find speed v if the distance traveled is one wavelength λ and the time of travel is the period T (which equals 1/frequency).
v = f • lambda
Compared to the mass of a proton, the mass of the electron is
very much less
A term for electric pressure is
voltage
A charged balloon illustrates that something can have a great amount of
voltage and a small potential energy.
Sound travels faster when the air is
warm.
