Questions and Answers of Physics Everyday Phenomena

What are we measuring when we perform a harmonic analysis of a sound wave? Explain.
Why is the second harmonic of a plucked guitar string likely to be stronger than the first harmonic or fundamental when the string is plucked in the usual position? Explain.
When you pluck a guitar string, are you likely to get a sound wave containing just a single frequency? Explain.
Is it possible for sound waves to travel through a vacuum? Explain.
A band playing on a flat-bed truck is approaching you rapidly near the end of a parade. Will you hear the same pitch for the various instruments as someone down the street who has already been passed
Is the wavelength of the fundamental standing wave in a tube open at both ends greater than, equal to, or less than the wavelength for the fundamental wave in a tube open at just one end? Explain.
If the temperature in an organ pipe increases above room temperature, thereby increasing the speed of sound waves in the pipe but not affecting the length of pipe significantly, what effect does this
Suppose that we increase the temperature of the air through which a sound wave is traveling.a. What effect does this have on the speed of the sound wave? Explain.b. For a given frequency, what effect
Is it possible for sound to travel through a steel bar? Explain.
Why is it much easier to produce longitudinal waves traveling in air than it is to produce transverse waves? Explain.
If we wrap a second wire around a guitar string to increase its mass, what effect does this have on the frequency and wavelength of the fundamental standing wave formed on that string? Explain.
If we increase the tension of a guitar string, what effect does this have on the frequency and wavelength of the fundamental standing wave formed on that string? Explain.
Is the distance between the antinodes of a standing wave equal to the wavelength of the two waves that interfere to form the standing wave? Explain.
A standing wave is produced on a string fixed at both ends so that there is a node in the middle as well as at either end. Will the frequency of this wave be greater than, equal to, or less than the
We can form standing waves on a rope attached to a wall by moving the opposite end of the rope up and down at an appropriate frequency. Where does the second wave come from that interferes with the
When two waves on separate ropes reach the spliced junction out of phase with one another, they interfere destructively producing no wave beyond the splice. What happens then to the energy carried by
Two ropes are joined smoothly to form a single rope, which is attached to a wall. If the ends of the two ropes are moved up and down in phase, but one rope is half a wavelength longer than the other
Is it possible for two waves traveling in the same direction to produce a wave (when they interfere) that has a smaller height (amplitude) than either of the individual waves? Explain.
Suppose that we increase the tension in a rope, keeping the frequency of oscillation of the end of the rope the same. What effect does this have on the wavelength of the wave produced? Explain.
Why is it easier to observe transverse waves on a heavy rope than on a light string? Explain.
What force causes individual segments of a rope to accelerate when a transverse pulse travels down the rope? Explain.
Suppose that we double the mass per unit of length of a rope by twining two ropes together. What effect does this have on the speed of a wave on this rope? Explain.
Is it possible to produce a longitudinal wave on a rope? Explain.
At sporting events the crowd sometimes generates a “wave” that propagates around the stadium. Is this wave transverse or longitudinal? What causes the wave to travel through the crowd? Explain.
Is it possible to produce a transverse wave on a Slinky? Explain.
If you increase the speed of a wave on a Slinky by increasing the tension but keep the same frequency of back-and forth motion, does the wavelength increase or decrease? Explain.
If you increase the frequency with which you are moving the end of a Slinky back and forth, does the wavelength of the wave on the Slinky increase or decrease? Explain.
A wave can be propagated on a blanket by holding adjacent corners in your hands and moving the end of the blanket up and down. Is this wave transverse or longitudinal? Explain.
A slowly moving engine bumps into a string of coupled railroad cars standing on a siding. A wave pulse is transmitted down the string of cars as each one bumps into the next one. Is this wave
Waves are traveling in an eastward direction on a lake. Is the water in the lake necessarily moving in that direction? Explain.
A wave pulse is transmitted down a Slinky, but the Slinky itself does not change position. Does a transfer of energy take place in this process? Explain.
A transformer is designed to step down line voltage of 110 V to 22 V. The primary coil has 400 turns of wire.a. How many turns of wire should there be on the secondary coil?b. If the current in the
A rectangular coil of wire has dimensions of 3 cm by 6 cm and is wound with 60 turns of wire. It is turned between the pole faces of a horseshoe magnet that produces an approximately uniform field of
A small metal ball with a charge of 0.05 C and a mass of 25 g (0.025 kg) enters a region where there is a magnetic field of 0.5 T. The ball is traveling with a velocity of 200 m/s in a direction
Two long parallel wires carry currents of 5 A and 10 A in opposite directions as shown in the diagram below. The distance between the wires is 5 cm.a. What is the magnitude of the force per unit
A step-up transformer is designed to produce 1380 V from a 115-V ac source. If there are 400 turns on the secondary coil, how many turns should be wound on the primary coil?
A step-down transformer is to be used to convert an ac voltage of 120 V to 6 V to power an electric train. If there are 300 turns in the primary coil, how many turns should there be in the secondary
If 6 A of current are supplied to the primary coil of the transformer in exercise 13, what is the effective current in the secondary coil?
A transformer has 15 turns of wire in its primary coil and 60 turns on its secondary coil.a. Is this a step-up or step-down transformer?b. If an alternating voltage with an effective voltage of 110 V
A coil of wire with 60 turns and a cross-sectional area of 0.02 m2 lies with its plane perpendicular to a magnetic field of magnitude 1.5 T. The coil is rapidly removed from the magnetic field in a
The magnetic flux through a coil of wire changes from 6 Tm2 to zero in a time of 0.25 s. What is the magnitude of the average voltage induced in the coil during this change?
A loop of wire enclosing an area of 0.03 m2 has a magnetic field passing through its plane at an angle to the plane. The component of the field perpendicular to the plane is 0.4 T, and the component
A coil of wire with 80 turns has a cross-sectional area of 0.04 m2. A magnetic field of 0.6 T passes through the coil. What is the total magnetic flux passing through the coil?
The magnetic force on a 30-cm straight segment of wire carrying a current of 5 A is 6 N. What is the magnitude of the component of magnetic field perpendicular to the wire?
A straight segment of wire has a length of 10 cm and carries a current of 5 A. It is oriented at right angles to a magnetic field of 0.6 T. What is the magnitude of the magnetic force on this segment
A particle with a charge of 0.06 C is moving at right angles to a uniform magnetic field with a strength of 0.5 T. The velocity of the charge is 600 m/s. What is the magnitude of the magnetic force
A wire carries a current of 4 A. How much charge flows past a point on the wire in a time of 5 s?
Two parallel wires, each carrying a current of 2 A, exert a force per unit length on each other of 1.6 x 10-5 N/m. What is the distance between the wires?
If the distance between the two wires in exercise 2 is tripled, how does the force per unit length change?
Two long parallel wires, each carrying a current of 4 A, lie a distance of 10 cm from each other. What is the magnetic force per unit length exerted by one wire on the other?
Two long bar magnets lying on a table with their south poles facing one another exert a force of 10 N on each other. If the distance between these two poles is doubled, what is the new value of this
By stepping up the voltage of an alternating-current source using a transformer, can we increase the amount of electrical energy drawn from the source? Explain.
Can a transformer be used, as shown in the diagram below, to step up the voltage of a battery? Explain. Q30 Diagram
A simple generator and a simple electric motor have very similar designs. Do they have the same function? Explain.
Does a simple generator produce a steady direct current? Explain.
If the magnetic field produced by the magnets in a generator is constant, does the magnetic flux through the generator coil change when it is turning? Explain.
Suppose that the magnetic flux through a coil of wire varies with time, as shown in the graph. Using the same time scale, sketch a graph showing how the induced voltage varies with time. Where does
Two coils of wire are identical except that coil A has twice as many turns of wire as coil B. If a magnetic field increases with time at the same rate through both coils, which coil (if either) has
A horizontal loop of wire has a magnetic field passing upward through the plane of the loop. If this magnetic field increases with time, is the direction of the induced current clockwise or
Is a magnetic flux the same as a magnetic field? Explain.
If Faraday wound enough turns of wire on the secondary coil of his iron ring, would he have found that a large steady-state current in the primary coil induced a current in the secondary coil?
Does an ac motor require a split-ring commutator to work? Explain.
In what respect is a simple ammeter designed to measure electric current like an electric motor? Explain.
Since the magnetic fields of a coil of wire and a bar magnet are identical, are there loops of current inside natural magnetic materials like iron or cobalt? Explain.
If the rectangular loop of wire shown in question 17 were oriented so that the plane of the loop is parallel to the magnetic field lines, would there be a net torque acting on the loop? Explain. в
A current-carrying rectangular loop of wire is placed in an external magnetic field with the directions of the current and field as shown in the diagram. In what direction will this loop tend to
If we were to represent the current loop of question 15 as a bar magnet or magnetic dipole, in what direction would the north pole be pointing? Explain.
If we look down at the top of a circular loop of wire whose plane is horizontal and that carries a current in the clockwise direction, what is the direction of the magnetic field at the center of the
Why does the magnetic force on a current-carrying segment of wire behave like one on a positive charge traveling in the same direction as the current? Explain.
If a uniform magnetic field is directed horizontally toward the east, and a negative charge is moving east through this field, is there a magnetic force on this charge, and if so, in what direction?
A uniform magnetic field is directed horizontally toward the north, and a positive charge is moving west through this field. Is there a magnetic force on this charge, and if so, in what direction?
Is the force exerted by one current-carrying wire on another due to electrostatic effects or to magnetic effects? Explain.
A horizontal wire is oriented along an east-west line, and a compass is placed above it. Will the needle of the compass deflect when a current flows through the wire from east to west, and if so, in
A horizontal wire is oriented along a north-south line, and a compass is placed above it. Will the needle of the compass deflect when a current flows through the wire, and if so, in what direction?
We visualized the magnetic field of the Earth by imagining that there is a bar magnet inside the Earth (fig. 14.8). Why did we draw this magnet with its south pole pointing north? Explain.
If we regard the Earth as magnet, does its magnetic north pole coincide with its geographic north pole? What defines the position of the geographic north pole? Explain.
Does a compass needle always point directly northward in the absence of other nearby magnets or currents? Explain.
Is it possible for a bar magnet to have just one pole? Explain.
In what respects is the force between two magnetic poles similar to the force between two charged particles? Explain.
If the distance between the south poles of two long bar magnets is reduced to half its original value, will the force between these poles be doubled? Explain.
The north pole of a hand-held bar magnet is brought near the north pole of a second bar magnet lying on a table. How will the second magnet tend to move? Explain.
A 600-W toaster, a 1200-W iron, and a 500-W food processor are all connected to the same 115-V household circuit, fused at 15 A.a. What is the current drawn by each of these appliances?b. If these
In the circuit shown, the 6-V battery is opposing the 9-V battery as they are positioned. The total voltage of the two batteries will be found by subtracting.a. What is the current flowing around the
Three 30-Ω light bulbs are connected in parallel to a 1.5-V battery with negligible internal resistance.a. What is the current flowing through the battery?b. What is the current flowing through each
In the circuit shown, the internal resistance of the battery can be considered negligible.a. What is the equivalent resistance of the two-resistor parallel combination?b. What is the total current
A clothes dryer uses 5500 W of power when connected to a 220-V ac line. How much current does the dryer draw from the line?
A toaster draws a current of 7 A when it is connected to a 110-V ac line.a. What is the power consumption of this toaster?b. What is the resistance of the heating element in the toaster?
A 60-W light bulb operates on an effective ac voltage of 110 V.a. What is the effective current through the light bulb?b. From Ohm’s law, what is the resistance of the light bulb?
A 30-Ω resistor has a voltage difference of 3 V across its leads.a. What is the current through the resistor?b. What is the power being dissipated in this resistor?
A 9-V battery in a simple circuit produces a current of 1.5 A through the circuit. How much power is being delivered by the battery?
Three identical resistances, each 24 Ω, are connected in parallel with one another as shown. The combination is connected to a 12-V battery whose internal resistance is negligible.a. What is the
Three resistors of 3 Ω, 6 Ω, and 2 Ω are connected in parallel with one another. What is the equivalent resistance of this combination?
Two resistors, each having a resistance of 8 Ω, are connected in parallel. What is the equivalent resistance of this combination?
Three resistors are connected to a 6-V battery as shown. The internal resistance of the battery is negligible.a. What is the current through the 15-Ω resistance?b. Does this same current flow
In the circuit shown, the 1-Ω resistance is the internal resistance of the battery and can be considered to be in series, as shown, with the battery and the 9-Ω load.a. What is the current flowing
A 40-Ω resistor and a 60-Ω resistor are connected in series to a 12-V battery.a. What is the current flowing through each resistor?b. What is the voltage difference across each resistor?
Three 20-Ω resistors are connected in series to a 6-V battery of negligible internal resistance.a. What is the current flowing through each resistor?b. What is the voltage difference across each
A current of 0.6 A flows through a resistor with a voltage difference of 120 V across it. What is the resistance of this resistor?
A current of 1.5 A is flowing through a resistance of 18 Ω. What is the voltage difference across this resistance?
A 24- resistor in a circuit has a voltage difference of 6 V across its leads. What is the current through this resistor?

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