Class 10 Science Chapter 11 Electricity
Electric Current and Electric Circut
Question :What is electricity?
Answer: The flow of electrons is called electricity.
Question : What is the electric circuit?
Answer: A continuous and closed path of an electric current is called an electric circuit.
Question :Electric current represent what
- Charge per unit
- Charge per unit time
- Charge per unit volume
- Charge per unit area
Question : What is electric current?
Answer :It is the rate of flow of electric charges in a given time in a cross section.
Questions :Which type of wire is used to constitute the flow of electrons?
Answer :Metallic wire
Question: State some difference between electric current and electric circuit?
Answer : Electric circuit – A continuous and closed path of an electric current is called an electric circuit.
Electric current – it is the rate of flow of electric charges in a given time.
Question: What happens if the circuit is broken?
Answer: if the circuit is broken the current stops flowing in it.
Question: How do we Express electric current ?
Answer: Electric current is expressed by the amount of charge flowing through a particular area in unit time, in other word it is the rate of flow of electric charges.
Question: What is the SI unit of electric charge?
Answer Coulomb (C).
Question 1 coulomb is equivalent to ?
Answer 6 x 1018 electrons.
Question: How much charge is contained in one electron?
Answer 1.6 x 10-19 c
Question: Which unit is used to express the electric current?
Answer: Ampere (A)
Question: Small quantity of current are expressed by what?
Answer: small quantity of current are expressed in miliampere or in microampere.
Question :1 milliampere and 1 microampere is equal to ?
Answer :1mA = 10-3 A and 1µA = 10-6 A
Question: Which instrument is used to measure electric current in a circuit?
Answer Ammeter.
Question :Write an electric current unit in ascending order?
Answer :Unit is ampere
Microampere, milliampere, ampere.
Question : In which direction does the electric current flows ?
Answer : the electric current flows in the circut from the positive terminal of the cell to the negative terminal of the cell .
Question :How does a metal conduct electricity?
Answer :Metals conduct electricity by moving or transferring its electron to another atom in metal.
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Electric Potential Difference
Question :What makes the charge flow?
Answer :Potential difference
Question:Why does the cell have to expend its chemical energy stored in it?
Answer : in order to maintain the current in a given electric circuit.
Question :What is the potential difference?
Answer :When electrons move only if there is a difference of electric pressure, called potential difference.
Question :Define electric potential difference with formula.
Answer :Electric potential difference between the two points in an electric circuit carrying some current from one point to another.
FORMULA :V=W/Q.
Question :What is the SI unit of potential difference ?
Answer : SI unit is Volt(V).
Question :Which device is used to measure V?
Answer :Voltmeter.
Question: Why is the voltmeter connected in parallel ?
Answer Voltmeter is Connected in parallel because, to measure potential difference of two ends of a resistor.
Question : Who was Alessandro volta?
Answer : He was an Italian physicist.
Question :Explain how 1 volt = 1 joule /1 coulomb?
Answer :When 1 joule of work is done to move a charge of one coulomb from one point to the other so we can call it 1 volt = 1 joule/1 coulomb.
Question :Voltmeter is always connected……..
- Vertical
- Series
- Parallel
- Horizontal
Question : Ammeter is connected in ……..
1- parallel
2- series
Question: Who discovered ampere law ?
Answer:Andre Marie Ampere.
Question: What is the SI unit of time?
Answer: Second.
Question: What is the formula of current with charge?
Answer: FORMULA: I=Q/t.
Question: 1 volt is equal to…
Answer : 1V =1J/1C.
Ohm’s Law
Question :Who found the relationship between current and potential difference?
Answer :German physicist George Simon Ohm.
Question :Explain ohm’s law?
Answer : The potential difference across the ends of a given metallic wire. its temperature remains the same, called ohm’s law.
Where, V=IR
If the potential difference is across the two ends of a conductor is 1V and the the current is one ampere then,
1 ohm=1 volt /ampere
:The current flow through the resistor is inversely proportional to resistance.
Questions: What is resistance ?
Answer: It is the property of a conductor to resist the flow of charge.
Questions: Who discovered the ohm?
Answer: Georg Simon ohm.
Questions: Who is Georg Simon ohm?
Answer: He is a German physicist.
Questions: Formula of current?
Answer: I=V/R.
Questions: What is the SI unit of resistance?
Answer: ohm
Questions: Which component is used to regulate electric current without changing the voltage?
Answer:Variable resistance.
Questions: Which device is used to change the resistance in the circuit?
Answer: Rheostat
Questions: What is a resistor?
Answer: a conductor having some applicable resistance is called a resistor.
Questions: What is a good and poor conductor of electricity?
Answer: a component of a given size that offers a low resistance is a good conductor.
a component of an identical size that offers a higher resistance is a poor conductor.
Questions: what is an insulator?
Answer: a component of the same size give even higher resistance than the poor conductor in which the electricity does not pass through it.
Factors on which the resistance of a conductor depends
Questions :What are the three factors on which resistance of the conductor depends?
Answer:1) On its length
2)On its area of cross section
3)On the nature of its material.
Question :Is there a relation between R and l and A?
Answer yes,R is directly propostional to L and A is inversly prpostional to R.
Questions: Which unit is constant in electrical resistivity?
Answer: rho is a constant.
Question what will you observe when the when we increase thickness of wire of the same material and of the same length
Answer we observed that the ammeter reading is increase because Resistivity of the wire will be less
Questions :Define electrical resistivity and its SI unit?
Answer:Where rho is a constant of proportionality and called electrical resistivity of the material of the conductor and its SI unit is ohm m.
Questions :Write the name of alloy or metal which has low resistivity? .
Answer: Metal which has low resistivity silver,copper,aluminium,Tungsten, etc.
Alloys which has low resistivity are constantan,Maganin, nichrome
Question: What is the electrical resistivity of silver and copper?
AnswerElectrical resistivity of silver 1.60 x10-8.
Electrical resistivity of copper 1.62 x 10-8.
Question: What is the resistivity of rubber and glass?
Answer Insulators like rubber and glass have resistivity of the order of 1012 to 1017 ohm metres.
Question :Why is alloy used for conducting electricity?f FFFd
Answer :resistivity of an alloy is generally higher than that of its constituents.Alloys do not oxidise readily at high temperature. For this reason they are used for conducting electricity.
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Question: Does the e www r Reddy of resistivity of material vary with temperature.
Answer yes.
- Questions : Why is tungsten used in bumilroflb filamentrd
Answer:Because tungsten has high resistivity as well be vmbas compared f deto copper and aluminium. Bff
Resistance of a system of resistors
Question: In how many ways resistors can be connected and explained?
Answer:Resistors can be connected in series and parallel. Oo FB b
1)Resistors in parallel :combination of resistors in which one or more resistors jare connected together betwelen a point, hence said to be parallel.
2)Resistors in series :In an electric circuit where one or lftb g hu fv VVji kimore resd cistors having resistance and joining end to end, hence are said to be series.
Questions What effect does happens to the voltage and current when resistors is connected in series
Answer:W c ee khen the resistor is connected in series the vol.ttage will be different at all points but current is constant in the k. circuit.
Que stions What effect does happen to the DDd and VG when resistor is connected in parallel
Answer: When the resistor is connected in parallel the voltage remains constant but the current will be diffdx DC d DD mmmcdderent at different points of circuit.
Questions: What is the formula of resistors in series?
Answer: R= R1+R2+R3.f
c
Cdc rrd: pdWhat is the Formula of a resistor in parallel?
Answddder: 1/R=1/R1+1/R2+1/R3.
c:cccc the disadvantage of a series circuit?
Answer: when series circuit is that when d DD c
c: f is the advantage of parallel circuits? Ex xsx DCC d DC xx ex xsx DD RR x
Answer: A parallel circuit divides the DD DD cf CR DD through the electric gadget,the total xd xd is helpful particularly wvv BChen each gadget has different resistance and reequirees different curr DD DD cdcdc Dent to c properly this type of circuit is majorly used at home electric wiring.s XD e DD f de c ee
Heating effect of electric current
When an dy electric fan becomes warm this shows which effect of electric current?
Answer: heating effect of electric currendt.
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Questions: What is the heating effect of electric current?d
DD xx gets dissipated entirely in the form of heat, this is known as the heating effect of electric current.
Question s Heating effect of electric current is utilised by which devices?
Answer: devices such as electric heater, electric iron etc.
Question :To maintain the current, the source has to expand its energy but where does its energy go?
Answer : this energy get dissipated in the resistor as heat
BB kk kb BB kk in parallel
Question:The power input to the circuit by the source. Explain with formula?
Answer :Let t be hmmthe time d i ki koi l kbh iring ok BB VG LLP which a charge Q flows across.
The work done in moving the charge through a potential differuence V is VQ therefore,the source must supply energy equal to o in time t hence the power input tol.
Questions: What is the joules hulaw of heating?
Answer: the energy dissipated in the resistor as heat thus for a stu gdy current I the amount of heat produced in a time t e Ti is this is known as a joule’s law of heating.
Questions: What does joule’s law of heating imply?
Answer:The law implies that heat produced in a resistor is
1 directly proportional to the square of current for a given resistance,
2 directly proportional to the resistance for a given current.
3 directly proportional to the time for which the current flows through the resistor.
Question:Define voltage source?
Answer : a voltage source is a two terminal device which can maintain a fixed voltage.
Practical applications of heating effect of electric current
Questions: What are the practical applications of heating effect of electric current ?
Answer: Heating effect of electric current has many useful applications such as the electric laundry iron electric toaster electric oven electric kettle and electric heater are some of their devices based heating effect.
Question : Name some familiar devices based on joules heating?
Answer :Electric geyser, electric heater, electric induction, electric iron, electric toaster.
Question: What is the other use of electric heating?
Answer:The electric heating is also used to produce light In a bulb.
Questions: Which metal is used to make filament of bulb?
Answer: Tungsten
Questions Why tungsten is used for making bulb filaments?
Answer: Because tungsten has a high melting point of 3380 C.
Questions: Which chemical gas is usually filled in a bulb?
Answer: The bulbs are usually filled with chemical inactive nitrogen and Argon gases to prolong the life of filament.
Questions: What is the use of a fuse?
Answer: It protects circuits and appliances by stopping the flow of any unduly high electric current.
Questions: Where the fuse is placed in the circuit?
Answer: The fuse is placed in series with the devices in the circuit.
Questions: What is a fuse?
Answer: Fuse is a piece of wire made up of metal or an alloy of appropriate melting point.
Questions: What happens if a current larger than a specific value flows through the circuit when the fuse is connected?
Answer: When the fuses connected in a circuit the temperature of the fuse wire will be increased and this will melt the fuse wire and break the circuit.
Questions: What rate of fuse is used for domestic purposes?
Answer: the fuses used for domain purpose are rated as 1A, 2A, 3A, 4A, 5A, 10A,etc
Questions: In which case the fuse must be used?
Answer: An electric iron which consumes 1kW electric power when operated at 220 V,a current of 1000/220 A that is 4.54A will flow in the circuit. In this case a 5A fuse must be used.
Electric power
Questions: What is electric power?
Answer: The rate at which electric energy is dissipated or consumed in an electric circuit is termed as electric power.
The power is given by
P = VI
P = I2R = V2 kkR
Questions: What is the SI unit of electric power? Ma
Answer: Watt (W)
Questions: Define 1 watt ?
Answer: it is the power consumed by a device that carries 1A of current when operated at a potential difference of 1V.
1W = 1volt x 1ampere = 1 V A
Questions: What is the larger unit of watt?
Answer: kilowatt and it is equal to 1000 watts.
Questions: Define watt hour?
Answer: when 1 watt of power is used for 1 hour (W h).
Questions: What is the commercial unit of electric energy?
Answer: kilowatt hour (kW h).