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Science MCQ (1 Marks)

Electric Current and its Effects · Bihar Board (BSEB) STD 7 (BSEB - English Medium). 151 questions.

Questions · Page 2 of 4

MCQ (1 Marks)

MCQ 511 Mark
The metal which is poor conductor of electricity is:
  • A
    Gold
  • B
    Iron
  • C
    Aluminium
  • ✓
    Tungsten
Answer
Correct option: D.
Tungsten
Tungsten is a poor conductor of electricity even though it is a metal.
But at high temperatures, it will conduct electricity.
As discussed above, it has a high melting point.
Therefore, high temperature doesn't have any bad effect on Tungsten.
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MCQ 521 Mark
Which of the following is the best option while considering the safety of household electric appliances?
  • A
    We should use wire strip as fuses.
  • B
    We should use non$-ISI$ marked $MCBs.$
  • ✓
    We should use $ISI$ marked $MCBs.$
  • D
    We should use conductors with high melting point in fuses.
Answer
Correct option: C.
We should use $ISI$ marked $MCBs.$
We should use $ISI$ marked $MCBs.$
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MCQ 531 Mark
A combination of two or more cells is called.
  • ✓
    A Battery.
  • B
    A Button cell.
  • C
    An Electric cell.
  • D
    Truck Battery.
Answer
Correct option: A.
A Battery.
A Battery.
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MCQ 541 Mark
An electron enters a magnetic field at right angles to it as shown in fig. The direction of the force acting on the electron will be:
  • A
    To the right.
  • B
    To the left.
  • C
    Out of the page.
  • ✓
    Into the page.
Answer
Correct option: D.
Into the page.
When a conductor carrying current is placed perpendicular to the direction of magnetic field, the force acting on it is given by Fleming's left hand rule. Since the direction of current is the same as that of the motion of a positive charge, the direction of force acting on it when moving perpendicular to the direction of magnetic field is the same as that acting on a current$-$carrying conductor placed perpendicular to the direction of magnetic field. Obviously, the force acting on an electron is opposite to that. Therefore in this case it is into the page.
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MCQ 551 Mark
The soft$-$iron core of an electromagnet loses its magnetism once the current passing through the electromagnetic coil stops because.
  • ✓
    Domains lose their alignment when the current is stopped.
  • B
    Iron cannot hold alignment for longer time even when the current is passing through the coil.
  • C
    Magnetic properties of iron are weak.
  • D
    Domains inside the iron get aligned in north to south direction.
Answer
Correct option: A.
Domains lose their alignment when the current is stopped.
As the current in coil flows due to electromagnetism, it behaves as magnet then the elementary magnets of soft iron core get attracted and on stopping current elementary magnets lose alignment.
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MCQ 561 Mark
When the two terminals of a battery are connected directly with a wire then:
  • A
    More electrical energy is stored in the cell.
  • ✓
    The chemicals get used up very fast.
  • C
    No current flows in the wire.
  • D
    None of these.
Answer
Correct option: B.
The chemicals get used up very fast.
When the two terminals of a battery are connected directly with a wire there will be a low resistance path for the current to flow.
The wire will get heated a little bit $($depends on the diameter of the wire less the diameter more heat$)$ and the battery will be quickly discharged.
During depletion, it may become very hot, emit gasses, and possibly explode.
The shorting wires will draw heavy current that may melt the wire or even cause them to soften and break.
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MCQ 571 Mark
The shorter line in the symbol of a electric cell represents:
  • A
    The positive terminal
  • ✓
    The negative terminal
  • C
    The direction of current
  • D
    All of these
Answer
Correct option: B.
The negative terminal
The shorter, thicker vertical line in the symbol of a cell represents the negative terminal. The longer, thinner vertical line in the symbol of a cell represents the positive terminal.
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MCQ 581 Mark
The coil of wire contained in heater is known as:
  • A
    Circuit.
  • B
    Component.
  • C
    Spring.
  • ✓
    Element.
Answer
Correct option: D.
Element.
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MCQ 591 Mark
Many devices such as.............. use batteries.
  • A
    Torches
  • B
    Transistors, toys
  • C
    $T.V.$ remote controls
  • ✓
    All of these
Answer
Correct option: D.
All of these

Torches
Transistors, toys
$T.V$ remote controls
All of these use batteries.

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MCQ 601 Mark
Exposed Electric doorbell can be damaged by:
  • A
    Mechanical damage
  • B
    High Electric currents
  • C
    Humidity
  • ✓
    All of the above
Answer
Correct option: D.
All of the above
  1. Mechanical Damage to metal gong or striker may hinder the working of the bell.
  2. High electric currents may cause heating and burning of an electrical circuit.
  3. Humidity may cause a short circuit between two unconnected wires, causing high electric currents and damage.
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MCQ 611 Mark
Which of these is not circuit element?
  • A
    Potential difference
  • B
    Voltmeter
  • ✓
    Resistor
  • D
    Battery
Answer
Correct option: C.
Resistor
Resistor is not a circuit element.
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MCQ 621 Mark
What does this symbol mean in electric circuit?
Image
  • ✓
    Switch
  • B
    Cell
  • C
    Resistance
  • D
    Battery
Answer
Correct option: A.
Switch
The given symbol is switch.
Used in the electric circuits.
An electric switch is a device that interrupts the electron flow in a circuit.
Switches are primarily binary devices: either fully on or off and light switches have a simple design.
When the switch is turned off, the circuit breaks, and the power flow is interrupted.
Circuits consist of a source of power and load.
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MCQ 631 Mark
Which component is this?
Image
  • A
    Capacitance
  • ✓
    Resistance
  • C
    Battery
  • D
    Inductance
Answer
Correct option: B.
Resistance
The given picture is of a resistance.
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MCQ 641 Mark
An element measure the flowing an electric current is:
  • A
    Voltmeter
  • B
    Filament
  • C
    Circuit
  • ✓
    Ammeter
Answer
Correct option: D.
Ammeter
The ammeter is used to measure, the rate at which the electrons flow through the globes and the voltmeter measures the potential drop that is actually the loss in potential energy as the electricity moves through the filament.
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MCQ 651 Mark
Electromagnet is used in:
  • A
    Battery
  • B
    Dry cell
  • ✓
    Electric bell
  • D
    Fuse
Answer
Correct option: C.
Electric bell
An electric bell is a mechanical or electronic bell that functions by means of an electromagnet.
When an electric current flows through the coils, the electromagnet creates a magnetic field which pulls the armature towards it, causing the hammer to strike the bell.
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MCQ 661 Mark
While making a battery $.........$ of a cell is connected to $.........$ of other cell.
  • A
    Negative terminal, negative terminal.
  • ✓
    Positive terminal, negative terminal.
  • C
    Positive terminal, positive terminal.
  • D
    Neutral terminal, negative terminal.
Answer
Correct option: B.
Positive terminal, negative terminal.
In order to make a battery the positive terminal of one cell is connected to the negative terminal of the other cell.
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MCQ 671 Mark
A circuit diagram represent on:
  • ✓
    Switch
  • B
    Electrical circuit
  • C
    Cells
  • D
    None of these
Answer
Correct option: A.
Switch
A circuit diagram represent on electrical circuit.
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MCQ 681 Mark
$A/ an...............$ is employed in an electric bell.
  • A
    Steel bar
  • ✓
    Electromagnet
  • C
    Permanent magnet
  • D
    Copper cylinder
Answer
Correct option: B.
Electromagnet
An electromagnet is employed in an electric bell.
When the push button is pressed the electric circuit is completed and the armature is attracted towards the electromagnet.
As a result, the small spring gets detached from the screw due to which the electric circuit is broken and the electromagnet is demagnetized.
Hence, the attraction disappears and the armature is brought back by the spring to its original position.
Contact of the spring with the screw is now remade, which completes the electric circuit.
The action is repeated over and over again continuously.
The armature vibrates and the hammer attached to it strikes the gong and the bell rings and sound is produced.
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MCQ 691 Mark
In electric bells, electrical energy transform into $.........$ energy.
  • A
    Mechanical
  • B
    Magnetic
  • ✓
    Sound
  • D
    Light
Answer
Correct option: C.
Sound
An electric bell is a mechanical or electronic bell that functions by means of an electromagnet.
When an electric current is applied, it produces a repetitive buzzing, clanging or ringing sound.
So clearly the electrical energy is converting into sound energy.
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MCQ 701 Mark
A safety device that cuts off the current in a circuit if a sudden heavy current starts flowing in it is:
  • ✓
    Fuse
  • B
    Ammeter
  • C
    Solenoid
  • D
    None of these
Answer
Correct option: A.
Fuse
Fuse is a safety device that cuts off the current.
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MCQ 711 Mark
Electromagnets are made up of:
  • A
    Steel
  • B
    Copper
  • ✓
    Soft iron
  • D
    Aluminum
Answer
Correct option: C.
Soft iron
Electromagnets are formed by the wounding of conducting wires like coil over the soft iron core.
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MCQ 721 Mark
Which material is used for making the armature of an electric bell?
  • ✓
    Soft iron
  • B
    Hard iron
  • C
    Nickel
  • D
    Any magnetic material
Answer
Correct option: A.
Soft iron
An electric bell is a mechanical or electronic bell that functions by means of an electromagnet.
When an electric current is applied, it produces a repetitive buzzing, clanging or ringing sound.
The material used for making the armature of an electric bell is soft iron which can induce magnetism rapidly.
Hence it can serve as a good electromagnet.
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MCQ 731 Mark
Fuse wire is generally made of:
  • ✓
    Tin and lead
  • B
    Nickel and chromium
  • C
    Nickel and copper
  • D
    Chromium and silver
Answer
Correct option: A.
Tin and lead
A fuse is an automatic means of removing power from a faulty system.
So, metals with low melting point and high resistance are used to make a fuse wire.
Therefore, tin or tin $-$ lead alloy whose melting point is low will be used in making fuse wire.
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MCQ 741 Mark
Which of the following is not a component of electric bell?
  • A
    Gong.
  • B
    Ferromagnetic strip.
  • ✓
    Low magnetic field permanent magnet to attract ferromagnetic strip.
  • D
    None of the above.
Answer
Correct option: C.
Low magnetic field permanent magnet to attract ferromagnetic strip.
Electric bell works on the mechanism of electromagnets $i.e,$ temporary magnets, and no permanent magnet is used.
Temporary magnet allows the ferromagnetic strip to return back to its initial state as switch is released.
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MCQ 751 Mark
An electromagnet is one which behaves as a magnet when current is $.........$
  • ✓
    Allowed to flow through.
  • B
    Not allowed to flow through.
  • C
    Stopped from flowing through it.
  • D
    None of these
Answer
Correct option: A.
Allowed to flow through.
Allowed to flow through.
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MCQ 761 Mark
Electric current has energy called:
  • A
    Voltmeter
  • B
    Filament
  • ✓
    Electrical energy
  • D
    None of these
Answer
Correct option: C.
Electrical energy
Electrical energy is caused by moving electric charges called electrons.
The faster the charges move, the more electrical energy they carry.
As the charges that cause the energy are moving, electrical energy is a form of kinetic energy.
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MCQ 771 Mark
When the current flowing through the fuse wire exceeds the safety limit, then it will be $.........$ breaking the circuit.
  • ✓
    Melted away.
  • B
    Remains the same.
  • C
    Damages the circuit.
  • D
    Makes the circuit remain connected.
Answer
Correct option: A.
Melted away.
Melted away.
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MCQ 781 Mark
If current does not flow through a circuit, then it is said to be an.
  • A
    Open circuit.
  • B
    Closed circuit.
  • C
    Incomplete circuit.
  • ✓
    Both $a$ and $c.$
Answer
Correct option: D.
Both $a$ and $c.$
Both $a$ and $c.$
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MCQ 791 Mark
Which power supply can be used in electric bell:
  • A
    $AC$
  • B
    $DC$
  • C
    Can't be predicted
  • ✓
    Both $A$ and $B$
Answer
Correct option: D.
Both $A$ and $B$

Electric bell works on the mechanism of electromagnets and for this, any type of power either $AC$ or $DC$ can be used.
An electric bell is a mechanical or electronic bell that functions by means of an electromagnet.
When an electric current is applied, it produces a repetitive buzzing, clanging, or ringing sound.

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MCQ 801 Mark
Electromagnets are used in which of the following?
  • A
    Speaker
  • B
    Motor
  • C
    Generator
  • ✓
    All of the above
Answer
Correct option: D.
All of the above
Electromagnets are formed by passing an electric current through a wire coiled around the substance with iron core.
Electromagnets are used to speaker, motor and generator.
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MCQ 811 Mark
Which of the following acts as safety device in electric appliances?
  • ✓
    Fuse.
  • B
    Connecting wires.
  • C
    Resistors.
  • D
    Battery.
Answer
Correct option: A.
Fuse.
Fuse.
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MCQ 821 Mark
The electric current flows from the end of cell marked $'+\ ’$ called the:
  • A
    Negative terminal
  • B
    Positive terminal
  • C
    Electric current
  • ✓
    None of these
Answer
Correct option: D.
None of these
The cell marked $'+\ ’$ is called positive terminal.
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MCQ 831 Mark
Electric Bell works on the principle:
  • A
    Electrical energy is converted into mechanical energy.
  • ✓
    Electrical energy is converted into sound energy.
  • C
    Mechanical energy is converted into sound energy.
  • D
    Sound energy is converted into electrical energy.
Answer
Correct option: B.
Electrical energy is converted into sound energy.
Electrical energy is converted into sound energy.
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MCQ 841 Mark
During a doorbell ringing:
  • A
    Current always flows in the circuit.
  • ✓
    Electromagnet is always present.
  • C
    Striker is always in contact with metal gong.
  • D
    Striker always repeatedly hits metal gong.
Answer
Correct option: B.
Electromagnet is always present.
Striker repeatedly hits the metal gong when doorbell is ringing.
This can be observed in regular bells used at homes.
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MCQ 851 Mark
What is $CFL?$
  • ✓
    Compact Fluorescent Lamp.
  • B
    Compact Fluorescent Lamina.
  • C
    Complete Fluorescent Light.
  • D
    Controlled Fluorescent Light.
Answer
Correct option: A.
Compact Fluorescent Lamp.

$CFL$ is Compact Fluorescent Lamp.
A compact fluorescent lamp, also called compact fluorescent light, energy - saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb; some types fit into light fixtures designed for incandescent bulbs.

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MCQ 861 Mark
Very strong electromagnets are used for lifting:
  • A
    Fans
  • B
    Washing machines
  • ✓
    Heavy iron pieces
  • D
    None of these
Answer
Correct option: C.
Heavy iron pieces
Very strong electromagnet is used for lifting iron pieces.
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MCQ 871 Mark
Circuit breaker device which can be used in place of fuse in domestic electric wiring is called:
  • A
    $DCB.$
  • B
    $MCD.$
  • ✓
    $MCB.$
  • D
    $BCM.$
Answer
Correct option: C.
$MCB.$
$MCB.$
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MCQ 881 Mark
The hammer hits the gong in an electric bell because:
  • A
    It has electric charge.
  • B
    It displays the spring effect.
  • ✓
    It is attracted towards the electro $-$ magnet.
  • D
    All of the above.
Answer
Correct option: C.
It is attracted towards the electro $-$ magnet.
The working of an electric magnet is based on the magnetic effect of current.
When the key is pressed the circuit gets completed and current passes through it causing the electromagnet to get magnetized which in turn attracts the armature.
This movement of the armature causes the hammer to strike the gong.
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MCQ 891 Mark
$MCB$ stands for:
  • A
    Main circuit board
  • B
    Master code bill
  • ✓
    Miniature circuit breaker
  • D
    None of these
Answer
Correct option: C.
Miniature circuit breaker

$MCB$ stands for Miniature circuit breaker.

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MCQ 901 Mark
The bulb glows as soon as the switch is moved to the:
  • ✓
    $‘ON’$ position
  • B
    $‘OFF’$ position
  • C
    Both $(a)$ and $(b)$
  • D
    None of these
Answer
Correct option: A.
$‘ON’$ position

The bulb glows as soon as the switch is $‘ON’$ position.

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MCQ 911 Mark
An electric bell works on the $.........$ effect of a current and uses an $.........$
  • A
    Magnetic, Permanent magnet
  • B
    Heating, Electromagnet
  • ✓
    Magnetic, Electromagnet
  • D
    Heating, Permanent magnet
Answer
Correct option: C.
Magnetic, Electromagnet
An electric bell works with the principle of working of electromagnetism.
When the switch is pushed on, the circuit gets completed and the current starts flowing through the $U -$ shaped electromagnet which creates a magnetic field in the core.
This attracts the iron armature.
When the armature moves towards the electromagnet, the hammer strikes the gong and the bell rings.
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MCQ 921 Mark
Name one device that uses an electromagnet.
  • ✓
    Electric bell
  • B
    Barometer
  • C
    Lactometer
  • D
    All the above
Answer
Correct option: A.
Electric bell
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.
The magnetic field disappears when the current is turned off.
Electromagnets usually consist of a large number of closely spaced turns of wire that create the magnetic field.
The wire turns are often wound around a magnetic core made of generally iron.
Electromagnets are widely used as components of electrical devices such as Electric Bell ,motors, generators, loudspeakers, hard disks, $\ce{MRI}$ machines, scientific instruments, etc.
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MCQ 931 Mark
A fuse is used in an electrical appliance:
  • A
    To earth the appliance.
  • ✓
    To protect the appliance and its cable.
  • C
    To change the efficiency of the applicance.
  • D
    To change the current rating of the applicance.
Answer
Correct option: B.
To protect the appliance and its cable.
Fuse is a device used to prevent overheating of appliances due to a sudden increase in the current in the circuit.
It protects the device and the user.
When the electric current is higher than the normal current needed by a circuit, the fuse blows up and breaks the circuit.
Hence, it protects the circuit from a power overload.
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MCQ 941 Mark
$.........$ piece is attracted by an electromagnet.
  • A
    Wood.
  • ✓
    Iron.
  • C
    Plastic.
  • D
    Rubber.
Answer
Correct option: B.
Iron.
Iron.
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MCQ 951 Mark
$.........$ is used to measure electric resistance in a circuit.
  • A
    Voltmeter
  • B
    Galvanometer
  • C
    Ammeter
  • ✓
    $\text{Ohm}$ meter
Answer
Correct option: D.
$\text{Ohm}$ meter
Step $-$ Check all options
$\text{Ohm}$ meter is used to measure electric resistance in a circuit.
Galvanometer $\rightarrow$ used to measure small current in a circuit.
Voltmeter $\rightarrow$ used to measure voltage
Ammeter $\rightarrow$ used to measure current
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MCQ 971 Mark
Which of the following precautions need not be taken while using electric gadgets/ appliances/ circuit?
  • A
    We should never touch a lighted electric bulb connected to the mains.
  • B
    We should never experiment with the electric supply from the mains or a generator or an inverter.
  • C
    We should never use just any wire or strip of metal in place of a fuse.
  • ✓
    We should never turn the switch in $ON$ position.
Answer
Correct option: D.
We should never turn the switch in $ON$ position.
We should never turn the switch in $ON$ position.
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MCQ 981 Mark
In making a battery
  • ✓
    Positive terminal of one cell is connected to the negative terminal of the next cell.
  • B
    Positive terminal of one cell is connected to the positive terminal of the next cell.
  • C
    Negative terminal of one cell is connected to the negative terminal of the next cell.
  • D
    None of the above.
Answer
Correct option: A.
Positive terminal of one cell is connected to the negative terminal of the next cell.
The positive terminal of one cell is connected to the negative terminal of the next cell.
Such a combination is called a battery.
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MCQ 991 Mark
Who discovered that when a compass needle is kept nearer to an electric circuit in which current is flowing, it deflects.
  • ✓
    Hans Christian Oersted.
  • B
    Michael Faraday.
  • C
    Galileo.
  • D
    Newton.
Answer
Correct option: A.
Hans Christian Oersted.
Hans Christian Oersted.
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MCQ 1001 Mark
The unit to measure electric resistance is:
  • A
    Joule.
  • ✓
    $\ce{Ohm}.$
  • C
    Ampere.
  • D
    Volt.
Answer
Correct option: B.
$\ce{Ohm}.$
$\ce{Ohm}.$
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