Physics exam 2
A chicken is cooked in a kitchen oven for an hour. Assume that the oven draws a current of 25.0A operates a voltage of 220V, and uses the electrical energy cost of 0.050 KWH approxemently how much does it cost cook the chicken?
$0.30
which statements are correct about an ammeter?
- it is always connected in series -it measures electrical current - it has low resistance
You have the resistors R1 is ^ R2 is 4 ^ and R3 is 10. Rank the following combinations based on the value of the resultant resistance with the highest at the top
-R1 R2 and R3 are all connected in series -R1 and R2 are connected in parallel and R3 is connected in series with the combination (R1 and R2) -R2 and R3 are connected in parallel, and R1 is connected in series with the combination (R2 and R3) -R1 R2 and R3 are all connected in parallel
in the figure shown the current flowing in each resisitor is ?
0.6 6v/10A
A resistance drop across a resisitor is 6.0V when a current of 3.0 A flows across the resisitor. The current that will produce a voltage drop of 5.0v across the resisitor is ? .
2.5
assuming all of these are passing through the same wire, rank the following cases based on the current with the highest at the top.
20 c charge passing every 1 second 100 c of charge passing every 10 seconds 50 c of charge passing every 10 seconds
a household ciruit rated at 120v is protected by a fuse rated 20A. The maximum number of identical 100w bulbs that can be lit stimutaneously in parallel with this ciruit wothout burning a fuse is
24 120*20=2400/100=24
A coil wire with 60 turns is placed in a magnetic field of 1 T. If the area of the coil is 0.06 m^2 and the flux changes to zero 0.5 s the inucedd voltage is ?V according to Faradays law
7.2
rank the following bulbs based on the value of their resisitance with the highest resistance at the top. The bulbs have power ratings for use on a 120 volt line.
A 60 W bulb A 100 W Bulb A 150W bulb
A current of 10.5 A flows through a battery for 3 minutes. How much charge passes through the battery in that time?
A charge of 1890 1890 Correct C passes through the battery in 3 minutes. Explanation The quantity of charge passing through the battery is determined using the following formula: q=It where I is the current flowing through the battery (A), q is the charge (C), and t is the time in seconds. Substituting the values in the equation, we get q=(10.5 A)×(180 s)= 1890 C
All of the following can be attracted to a magnet except
A copper wire
An AC frequency of 50 Hz means that ?
A current changes direction 50 times each second
inside a battery
A positive charge is always pushed toward the positive terminal the negative charge is pushed toward the negative terminal
which of the following are essential elements of an electrical circuit?
A source of electricity, A closed path
There are three identical lamps A1 A2, and A3 in a circuit A1 and A2 are connected in a parallel, and A3 is connected in a series to the parallel combination. ( A1 and A2). If lamp A1 turns off what happens to the brightness of A2 and A3?
A2 gets brighter A3 gets dimmer
According to the figure F1 and F2 produce no torque becuase they are
Acting in opposite directions in the same line of action
According to the figure the pointer of the galvanometer does not deflect unless the current is ? .
Alternating
Which of the following is an application of a current carrying wire placed in a magnetic field.
An ammeter An electric motor
two light bulbs A and B are connected in series so they carry the same current. Light bulb A is brighter than light BUlb B. Which bulb has greater ressistance?
Bulb A has greater resistance
you have identical magnets A, B, and C falling fromthe same height magnet A is falling through an incomplete copper ring. Magnet B is falling through a complete copper ring, Magnet C is falling through a coil of many turns. Rank the magnets according to the time it takes to reach the floor.
C B A
A battery provides the energy needed to move electrical forces through a circuit. Where does the energy from the battery come from?
Chemical reactions
Near your home a step down transfromer is operating on the utility pole when the voltage is stepped down the ? increases
Current
in ohm's law (^v=I*R) I represents the ? in units of ? . While R represents the ? in units of ? .
Current, ampere Resistance, Ohm
THe magnetic force per unit length between two identical parallel current carrying wires is?
Directly proportional to the current directly proportional to the the length of the wires Inversly proportional to the distance between the wires.
two current carrying parallel wires are exertigna force of 5 newtons on eachother which of the following changes would not change the force between them
Double the length and cut one current in half cut the length in half and reduce the seperation by half
In what respects is the force between two magnetic poles similar to the force between two charged particles?
Explanation Both are central forces with the property that likes repel and unlikes attrac
If the distance between the south poles two long bar magnets is reduced to half its original value, how will the force between the poles change?
Explanation Decreasing the distance between the two south poles will quadruple the repulsive force between them. The force law for magnetic poles, like that for electric charges, varies inversely with the square of the distance.
A 115-W light bulb operates on an effective ac voltage of 110 V. What is the effective current through the light bulb?
Explanation The current through the light bulb is given by I=PV=115 W110 V I=1.0455 A
How many poles can a bar magnet have?
Explanation The existence of an isolated magnetic pole has never been confirmed and bar magnets are always only two poles
A simple generator and a simple electric motor have very similar designs. Do they have the same function?
Explanation The function of the motor is to convert electrical energy into mechanical energy. The function of the generator is to convert mechanical energy into electrical energy. In the process of running, a motor does generate a back or counter emf that reduces the current that it would draw based strictly on the resistance of its windings.
The north pole of a hand-held bar magnet is brought near the north pole of a second bar magnet lying on the tablet. How will the second magnet tend to move?
Explanation The second magnet will be repelled and move away according to the rule that like magnetic poles repel one another.
Do the sensors that detect vehicles at stoplights depend on the weight of a vehicle to trigger the change?
Explanation The sensors depend on a loop of wire whose inductance changes when your car (with lots of metal in it) goes over the loop.
which statements are true about the voltmeter?
It has high ressistance It is always connected in parallel it measures the voltage
the unit of electromotive force (emf) of a battery is the
Joule/coulomb
Which are correct about magnetic and electric field lines?
Magentic fields emerge from the north pole and go into the south pole. while electric field lines originate from the positive pole and end on the negative pole. Magnetic field lines make continuous loops while electric field lines do not.
A fuse
Melts with high current and opens the circuit helps protect against high current Is always connected in series
Magnetic field force is measured in Teslas (T) another way to express this unit is as ?
N/A*m
Household circuits are always connected in ?
Parallel Parallel and circuits
in electrical cirucits the voltmeter is always connected in ? while the Ammeter is always connected in ?
Parallel Series
If you think the electeic circuit as analogous to the plumbing system in your home than the voltage in an electric circuit corresponds to corresponds to ? in a water pipe.
Pressure
What does a battery do with the energy it gains?
Seperates the positive and negative charges does work to increase the electrical energy
Match the following pairs based on their function shown in the figure
Spring- controls the movement of the pointer The iron core Strengthens the magnetic field Magnet Provides the external magnetic field The pointer -Deflects with the coil to indicate the current
THe number of coils in the secindary coil of a transformer is larger than that of the primary coil the voltage will?
Step up
Rank the following cases based on the degree of deflectionof a compass placed beside a current carrying wire with the greatest defletion to the top
THe compass is placed 5cm from a wire carrying 10 A The wire is placed 5cm from a wire carrying 5A The compass is placed 10 CM from a wire carrying 5A
Three resistors - R1 = 16 Ω, R2 = 22 Ω, and R3 = 26 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the current coming from the battery?
The current coming from the battery is 0.1875 0.1875 Correct A. Explanation The current from the battery is calculated using Ohm's law as follows I=VR where V is the voltage of the battery, and R is the total resistance. The total resistance in the circuit is calculated as follows Rseries=16 Ω+22 Ω+26 Ω Rseries=64 Ω Substituting values in the equation, we get I=12 V64 Ω=0.1875 A
Three resistors - R1 = 16 Ω, R2 = 22 Ω, and R3 = 26 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the current coming from the battery?
The current coming from the battery is 0.1875 0.1875 Correct A. Explanation The current from the battery is calculated using Ohm's law as follows I=VR where V is the voltage of the battery, and R is the total resistance. The total resistance in the circuit is calculated as follows Rseries=16 Ω+22 Ω+26 Ω Rseries=64 Ω Substituting values in the equation, we get I=12 V64 Ω=0.1875 A
Four 46-Ω resistors are connected in series to a 18-V battery of negligible internal resistance. Calculate the current flowing through each resistor.
The current flowing through each resistor is 0.097 0.097 Correct A. Explanation The total series resistance is determined using the following formula: Rseries= R1+ R2+ R3 +R4=4×46 Ω Rseries= 184 Ω The current flowing through each resistor is determined using Ohm's law. V= IR, I= VRseries
A 46-Ω resistor and a 28-Ω resistor are connected in series to a 12-V battery of negligible resistance. What is the current flowing through each resistor?
The current flowing through each resistor is 0.162 0.162 Correct A. Explanation The total resistance is calculated using the formula: Rseries=R1+R2=46 Ω + 28 Ω=74 Ω The current flowing through each resistor is determined using Ohm's law. V= IR, I= VRseries
Three resistors - R1 = 16 Ω, R2 = 22 Ω, and R3 = 26 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the current through the 16-Ω resistor?
The current is 0.1875 0.1875 Correct A. Explanation The total resistance of the circuit is R=R1+R2+R3=16 Ω+22 Ω+26 Ω R=64 Ω The current through the 22-Ω resistor is I=VR=12 V64 Ω I=0.1875 A
A 120 ohm resistor and a 34 ohm resistor are connected in a series with a power supply. which statements are correct
The current is the same through both resistors The voltage drop across the 120 ohm resistor is larger than the drop across the 34 ohm resisitor
which is true about the current flowing through a series circuit?
The current provided by the power source flows equally through each of the resistors in a circuit
A 86-Ω resistor has a voltage difference of 15 V across its leads. What is the current through the resistor?
The current through the resistor is 0.1744 0.1744 Correct A. Explanation The current through the resistor is determined using the following formula I=VR=15 V86 Ω I=0.1744 A
A charge of 34 C passes at a steady rate through a resistor in 7 s. Determine the current through the resistor.
The current through the resistor is 4.85 4.85 Correct A. Electric current is the rate of flow of electric charge. It is determined using the following formula: I=qt=34 C7 s= 4.8571 A where I is the current, q is the charge passing through the resistor, and t is the time.
Choose the correct statements about the magnetic force of a charge moving in a magnetic field
The force is directly propertional to the amount of charge the force is directly proportional to the strength of the magnetic field
The time required for one complete cycle of a mass oscillating at the end of a spring is 0.55 s. What is the frequency of oscillation?
The frequency of oscillation is 1.81 1.81 Correct Hz. Explanation The frequency is calculated as follows: f=1T=10.55 s=1.81 Hz
Match the following pairs to form a complete senetence
The magneticfield lines around the current carrying wire are in the shape of-concentric fields The right hand rule states that the thumb points- in the directions of the current The direction of the magnetic field around a carrying wire is -Perpindicular to the current. The right hand rule sates that the fingers curl around the wire in the direction of- the magnetic field
The magnetic flux through a loop is proportional to
The magnitude of the magnetic field The area bonded by the loop
Two long bar magnets lying on a table with their south poles facing each other exert a force of 49 N on each other. If the distance between these two poles is tripled, what is the new value of this force?
The new value of the force is 5.44 5.44 Correct N. Explanation The magnetic force is inversely proportional to the square of the distance between the two poles. The new force is calculated as follows: Fnew∝1(3r)2=19r2 Fnew=F9 Fnew=49 N9=5.4444 N
The frequency of oscillation of a pendulum is 22 cycles/s. What is the period of oscillation?
The period of oscillation of the pendulum is 0.045 0.045 Correct s. Explanation The time period is calculated as follows: T=1f=122 Hz=0.0455 s
A 86-Ω resistor has a voltage difference of 15 V across its leads. What is the power being dissipated in this resistor?
The power dissipated is 2.616 2.616 Correct W. Explanation The current through the resistor is determined using the following formula I=VR=15 V86 Ω I=0.1744 A The total power dissipated in the resistor is calculated as follows P=V×I=15 V × 0.1744 A P=2.6163 W
A toaster draws a current of 15 A when it is connected to a 110-V ac line. What is the resistance of the heating element in the toaster?
The resistance of the heating element in the toaster is 7.33 7.33 Correct Ω. Explanation The resistance of the heating element in the toaster is determined using the following formula R=VI=110 V15 A R=7.3333 Ω
A 115-W light bulb operates on an effective ac voltage of 110 V. Calculate the resistance of the light bulb using Ohm's law.
The resistance of the light bulb is 105.212 105.212 Correct Ω. Explanation The current through the light bulb is given by I=PV=115 W110 V I=1.0455 A
A current of 1.522 A flows through a resistor with a voltage difference of 115 V across it. Determine the resistance of this resistor.
The resistance of the resistor is 75.55 75.55 Correct Ω. Explanation The resistance is calculated using Ohm's law. We know that V=IR . From this, we get R=VI Substituting the values in the equation, we get R=115 V1.522 A=75.5585 Ω where I is the current, R is the resistance, and V is the voltage.
match the following based on their function shown in the figure
The spring- controls the movement of the pointer The iron core- strengthens the magnetic field THe magnet- provides the externalmagnetic field THe pointer-deflects with the coil to indicate the current
match the following pairs to those of the right hand rule.
The thumb -indicates the magnetic force The index finger- indicates the direction of the velocity of the moving charge The middle finger- indicates the direction of the magnetic field
A toaster draws a current of 15 A when it is connected to a 110-V ac line. What is the power consumption of this toaster?
The toaster consumes a power of 1650 1650 Correct W. Explanation The power consumption of the toaster is determined using the formula P=V×I=110 V×15 A P=1650 W
Three resistors - R1 = 16 Ω, R2 = 22 Ω, and R3 = 26 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the total resistance in the circuit?
The total resistance in the circuit is 64 64 Correct Ω. Explanation The equivalent series resistance of a circuit is calculated as follows Rseries=R1+R2+R3+......Rn The total resistance in the circuit is calculated as follows Rseries=16 Ω+22 Ω+26 Ω Rseries=64 Ω
A 46-Ω resistor and a 28-Ω resistor are connected in series to a 12-V battery of negligible resistance. What is the voltage difference across each resistor?
The value of v1 across a 46-Ω resistor is 7.452 7.452 Correct V. The value of v2 across a 28-Ω resistor is 4.536 4.536 Correct V. Explanation The voltage across each resistor is determined using Ohm's law. The total resistance is calculated using the formula: Rseries=R1+R2=46 Ω + 28 Ω=74 Ω The current flowing through each resistor is determined using Ohm's law.
Suppose that water waves have a wavelength of 4.4 m and a period of 1.7 s. What is the velocity of these waves?
The velocity of the waves is 2.58 2.58 Correct m/s. Explanation The velocity of the water waves is calculated using the following formula: ν=λT=4.4 m1.7 s=2.5882 m/s where v is the velocity, λ is the wavelength, and T is the period.
Four 46-Ω resistors are connected in series to a 18-V battery of negligible internal resistance. Determine the voltage difference across each resistor.
The voltage difference across each resistor is 4.5 4.5 Correct V. Explanation The voltage across each resistor is determined using Ohm's law. V=IR The total series resistance is determined using the following formula: Rseries= R1+ R2+ R3 +R4=4×46 Ω
A current of 1.5 A is flowing through a resistance of 32 Ω. What is the voltage difference across this resistance?
The voltage difference across this resistance is 48 48 Correct V. Explanation The voltage across the resistance is determined using Ohm's law. Ohm's law states that V=IR where V is the voltage, I is the current, and R is the resistance. Substituting the values in the equation, we get V=1.5 A×32 Ω =48 V where I is the current, R is the resistance, and V is the voltage.
Three resistors - R1 = 16 Ω, R2 = 22 Ω, and R3 = 26 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. What is the voltage difference across the 22-Ω resistor?
The voltage difference is 4.125 4.125 Correct V. Explanation The total resistance of the circuit is R=R1+R2+R3=16 Ω+22 Ω+26 Ω R=64 Ω The current through the 22-Ω resistor is I=VR=12 V64 Ω I=0.1875 A The voltage difference across the 22-Ω resistor is ΔV=IR=0.1875 A×22 Ω ΔV=4.13 V
Suppose that water waves coming into a dock have a velocity of 2.1 m/s and a wavelength of 7 m. With what frequency do these waves meet the dock?
The water waves meet the dock with a frequency of 0.3 0.3 Correct Hz. Explanation The frequency of the water waves is calculated using the following formula: f=νλ=2.1 m/s7 m=0.3 Hz where f is the frequency, v is the velocity, and λ is the wavelength.
If the frequency of the wave is 4 Hz, what is the wave speed?
The wave speed is 18 18 Correct m/s. Explanation The wave speed is calculated using the following formula: ν=f×λ=4 Hz ×4.5 m=18 m/s
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. A wave on a rope is shown as in the diagram, where L = 9 m. What is the wavelength of this wave? (You must provide an answer before moving to the next part.)
The wavelength of the wave is 4.5 4.5 Correct m. Explanation The wavelength of the wave is calculated as follows: λ=L2=9 m2=4.5 m
Three resistors - R1 = 16 Ω, R2 = 22 Ω, and R3 = 26 Ω are connected to a 12-V battery as shown in the figure. The internal resistance of the battery is negligible. Is the current flow through resistor R1 same as the current flow through resistor R3 in the given circuit?
Yes
THe current produced froma simple elctrical generator is ?
alternating
a current carrying circular loop is considered a dipole magnet because of its shape around the magnetic field is similar to that of a ? magnet.
bar
We visualize the magnetic field of the Earth by imagining that there is a bar magnet inside the Earth. Why did we draw this magnet with its south pole pointing north?
because the South Magnetic Pole of the Earth attracts North-seeking magnets, which is in the geographic North pole magnetic polesCorrect
you have a 1.5 V flashlight battery, a 10 ohm resistor a 5 ohm resistor and a flashlight lamp. in which of the following circuit connections will the flashlight lamo be the brightest.
connect the lamp in a parallel with both the battery and the 5 ohm resisitor connect the lamp in parallel with both the battery and 10 ohm resistor connect the lamp directly to the battery without using the resisitor
A breaker opens the circuit when high ? passes
current
KWH is a unit of ?
energy
What does the electrical company actually sell you?
energy
An ampere is
equal to one columb/ a second a unit of electric current
The flament of the lightbulb heats up because
flowing electrons lose kinetic energy through collisions with other electrons in the flament
A 52-Ω resistor in a circuit has a voltage difference of 8 V across its leads. Calculate the current through the resistor.
he current through the resistor is 0.153 0.153 Correct A. Explanation The current through the resistor is determined using Ohm's law. We know that V=IR . From this, we get I=VR . Substituting the values in the equation, we get I=8 V52 Ω= 0.1538 A where I is the current, R is the resistance, and V is the voltage.
The magnetic flux is the ? of the magnetic field lines passing through the loop
number
if you load a circuit in your home with too many devices- like light bulbs, toasters, and stereos in ? you can overload the ciruit and trip a circuit breaker to blow a fuse
parallel
the effective current found from a sinusodal circuit is 0.707 times the value of the ? current.
peak
The two ends of a magnet are called?
poles
which of the following would be called an electrical current moving toward the left
positve charges moving to the left negative charges moving to the right
A sound wave is composed of?
regions of low pressure regions of high pressure
The ? of a wave can be found by multiplying the wavelength by the frequency
speed
Wires are used to connect a battery and a lightbulb in a circuit as the battery gets older
the current in the circuit goes down the chemical reaction in the battery is depleted the internal resisitance in the battery increases
you have a circuit made out of battery some wire, and a light bulb, if you add an additonal bulb to the circuit in series with the first bulb
the current will decrease
In AC circuits, current is often expressed as an effective value rather than an average because.
the effective value is always positive the average value is always zero
A positively charged particle is momentarily at rest in a uniform magnetic field directed horizontally towards the north. In what direction, if at all, is the magnetic force on the particle?
there is no magnetic force on the particle
A positivecharge is moving from left to right on the magnetic field directed into the page the direction of the magnetic force acting on the charge is?
upward
the increase in electric potential energy due to the seperation of the positive and negative charges produces a ? diffrence between the two terminals of the battery
voltage
if you think of an electrical circuit as an analogous to the plumbing system in your home, than the charges in an electric cicruit correspond to the ? in a plumbing system
water
