PRACTICE PAPER
SUB : PHYSICS (2020)
ELECTRICITY
ELECTRICITY
CLASS X ______________________________________________________________________________
I. Very short answer type questions:
- Define charge. Give its S.I unit.
- Define one ohm.
- State Coulomb’s law.
- What do you mean by the statement “Potential difference between points A and B in an electric field is 3 volt”?
- Give the relation between 1 volt, 1 joule, and 1 coulomb. Name the physical quantity.
- The length of a wire is doubled. How is its resistivity affected?
- A current of 1 A is drawn by a filament of an electric bulb. What would be the number of an electron passing through a cross-section of the filament in 16 s?
- A cylindrical conductor of length 'l' and uniform area of cross-section 'A' has resistance 'R'. What is the area of cross-section of another conductor of length '2l' and resistance 'R' of the same material?
- What is the maximum resistance which can be made by using five resistors each of 1/5 Ω?
- What is the minimum resistance which can be made by using five resistors each of 1/5 Ω?
- What
is the minimum resistance that can be made by using 2 Ω, 3 Ω and 5 Ω?
- Which is having more resistance a 50 W bulb or a 25 W bulb?
- Write an expression for voltage (V).
- If the current I through a resistor is increased by 100% at a constant temperature, what will be the increase in power dissipated?
- Write the relation between resistance (R) of the filament of a bulb its power (P) and a constant voltage (V) applied across it.
- The voltage-current (V-I) graph of a metallic conductor at two different temperatures T1 and T2 is shown in Fig 1. At what temperature is the resistance higher?
- Name the physical quantity whose unit is volt/ampere.
- A given length of a wire is doubled on itself and this process is repeated once again. By what factor does the resistance of the wire changes?
- 400 J of heat is produced in 4 s.in a 4Ω resistor. Find potential difference across the resistors.
- Which is having more resistance R - 220 V,100 W bulb or a 220 V, 60 W bulb?
- What is meant by the potential difference between two points?
- In a circuit, if two resistors of 5 Ω and 10 Ω are connected in series, compare the current passing through the two resistors?
- What is the commercial unit of energy?
- Name the instrument used for the measure in
(a) Potential difference (b) Current - How is an ammeter connected in a circuit to measure the current flowing through it?
- What happened to the resistance of a conductor when its area of cross-section is increased?
- Through which of the two wires of the electric current will flow more easily
(a) a thick wire or
(b) a thin wire of the same material and of the same length when connected to the same source. - What is electric power? State its SI unit.
- State in brief the meaning of an electric circuit.
- Keeping the potential difference constant the resistance of an electric circuit is doubled. State the change in the reading of an ammeter connected in the circuit.
- Draw a simple circuit diagram that can be used to verify Ohm’s law.
II. Short answer type questions:
- Calculate the number of electrons constituting one coulomb of charge. Charge on 1 electron =1.6 ×10-19 .
- Two resistors are connected in series and in parallel, what effect will it have on the reading of voltmeter and ammeter?
- While performing an experiment to study the dependence of current on p.d a student keeps the circuit closed for a long time to measure the current and P.d, state, have the resistance of the resistor will be affected?
- State in brief the meaning of a variable resistor. Draw a circuit diagram to illustrate the function especially in the study of variation in current with a potential difference across the resistor.
- What is a fuse? Can we use 5 amp fuse in 15 amp wire or vice versa? Why? Name commonly used materials for making fuse?
- What is the usual current rating of the fuse wire in the line to feed
(a) Lights and fans
(b) Appliances of 2KW or more power? - State Ohm’s law.
- What is earthling? What is the colour of an earth wire?
- Explain what is short-circuiting in electric supply.
- What is the function of the earth wire in the electrical instruments?
- What do you understand by frictional electricity? Why is it also known as static electricity?
- The resistance of a resistor is kept constant and the potential difference across its two ends is decreased of half of its former value. State the change that will occur in the current through it.
- Name the physical quantity which is the same in all the resistors when they are connected in series.
- Light from a bathroom bulb gets dimmer for a moment when the geyser is switched on. Why?
- Ammeter burns out when connected in parallel. Give reason.
- Define electric current. Name the particles that constitute electric current flowing through metallic wires. Calculate the resistance of a metal wire of length 2 m and area of cross-section 1.55×10-6 sq. If the resistivity of the metal is 2.8×10-8 ohm.
- An electric heater rated 800 W operates 6 hr/day. Find the cost of energy to operate it for 30 days at Rs 3 per unit.
- (a)Why are electric was filled with chemically inactive nitrogen or argon?
(b)What is meant by the statement that the rating of a fuse in a circuit is 5 A? - What are superconductors? Give an example.
- Cu and Al wires are used for electricity transmission. Give reasons.
- An electric wire is stretched to increase its length by 25%. By what percentage will the resistance be increased and what will be increased in its resistivity?
- How much current will an electric bulb draw from 220-volt source if the resistance of the bulb is 1200Ω? If in place of a bulb, a heater of resistance 100Ω is connected to the sources, calculate the current drawn by it.
- State the factors on which at a given temperature the resistance of a cylindrical conductor depends. State the SI unit of electricity.
- A battery of 12 volts is connected to a series combination of resistance 3 ohm 4Ω 5Ω and 12Ω. How much current would flow through the 12Ω resistor?
- Explain two disadvantages of series arrangements for household circuits.
- Give reasons for the following:
(a) An electric bulb is usually filled with chemically inactive gases like nitrogen and Argon.
(b) Fuse wire is placed in series with the device. - Draw a schematic diagram of an electric circuit comprising of 3 cells and an electric bulb. Ammeter plug key ON mode and another with the same components but with two bulbs in parallel and a voltmeter across the combination.
- Calculate the work done in moving a charge of 2 coulombs across two points having a potential difference of 12 V.
- List in a tabular for two differences between a voltmeter and an ammeter.
- State the physical quantity which equals the ratio of potential difference and current. Define its SI unit.
- Mention the condition under which charges can move in a conductor. Name the device which is used to maintain this condition in an electric circuit.
- Draw a schematic circuit diagram for a circuit in which three resistors R1, R2 and R3 a plug key under closed condition an ammeter are joined in series with a 5-volt battery. Also, a voltmeter is connected to measure the potential difference across the resistance R1.
- Define 1 volt. State the relation between work, charge and potential difference for an electric circuit. Calculate the potential difference between two terminals of the battery if 100 joules of work are required to transfer 20 coulombs of charge from one terminal of the battery to the other.
- Name the physical quantity that determines the rate at which energy is delivered by an electric current. State and define the unit of this physical quantity.
- State the factors on which the heat produced in a current-carrying conductor depends. Give one particular application of this affect.H = I2Rt.
- An electric iron takes a current of 5A and develops 1.5 × 104 J of heat energy in 30 sec. Calculate the resistance of the electric iron.
- Derive an expression for electric energy consumed in a device in terms of V, I and t, where V is the potential difference applied to it, I is the current drawn by it and t is the time for which the current flows?
III. Long answer type questions:
- A hot plate connected to a 220 V line has two resistance coils A and B, each of 22-ohm resistance. Calculate the amount of electric current flowing when these coils are:
(i) Used individually (ii) Connected in series (iii)Connected in parallel. - A torch bulb is rated 5 volts and 500 mA. Calculate its
(i) power (ii)resistance (iii) energy consumed when it is lighted for 4 hours. - Derive the relation for equivalent resistance when two resistances are connected parallel.
- Which consumes more energy a 250 watt TV set in 1 hour or 1200 W toaster in 10 min?
- An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 sec.
- An electric lamp is marked 20 W, 220 V. It is used for 10 hours daily. Calculate:
(a) Its resistance while glowing.
(b) No.of units consumed every day. - (a) Nichrome wire of length l and radius r has a resistance of 10Ω. How would the resistance of the wire change when:
(i) Only the length of the wire is doubled?
(ii) Only the diameter of the wire is doubled. Justify your answer?
(b) Why elements of electrical heating devices are made up of alloys. - How would you connect three resistors each of resistance 6Ω so that the combination has a resistance of (i) 9Ω (ii) 4Ω? Justify your answer.
- (a)Define the electric power of a device of resistance R is connected across a source of V voltage and draws a current I. Derive an expression for power in terms of voltage and resistance.
(b) An electric bulb is connected to a 220 V generator. The current is 0.5 A. What is the power of the bulb? - Explain the following:
(i) The elements of electric heater devices such as bread toaster and electric iron are made of an alloy rather than of pure metal.
(ii) A series arrangement is not used for domestic circuits.
(iii) Copper and Aluminum wires are usually employed for electricity transmission. - (i) Calculate electrical energy consumed by a 1200 W toaster in 30 minutes.
(ii) What will be the cost of using the same for 1 month if 1 unit of electricity cost rupees 4? - Three resistance of 5Ω, 10Ω and 15Ω are connected in series and combination is connected to battery 30 volts. Ammeter and Voltmeter are connected in the circuit. Draw a circuit diagram to connect all the devices in the proper correct order. What are the current flowing and potential difference across 10Ω resistance?
- An electric iron consumes energy 840 W when hitting is at the maximum and 360 W when the heating is at the minimum. The voltage at which it is running is 220 V. What are the current and resistance in each case?
- Define resistance. Write the S.I unit of resistance.
- Match the correct range of resistivity with the materials given:
(a) Conductor and insulators (i)10-6 ohm
(b) Alloys (ii) 1012 to 1017
(c) Insulator (iii) 10-6 to 10-8. - A lamp rated 60 W and an electric iron rated 800 W are used for 6 hours every day. Calculate the total energy consumed in 30 days.
- (a)Draw a diagram to show how to register R1 and R2 are connected in parallel.
(b)In a circuit, if two resistors of 4Ω and 8Ω are connected in parallel, find out the ratio of current, passing through the two resistors. - Name and define the S.I unit of resistance. Calculate the resistance of a resistor if the current flowing through it is 200mA when the applied potential difference is 0.8 volt.
- Draw a schematic diagram of a circuit consisting of a battery of five 2V cells, are a 5Ω,10Ω and 15Ω resistor and a plug key are all connected in series. Calculate the electric current passing through the circuit when the key is closed.
- A wire of resistance R is cut into 5 equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R'. Calculate the ratio R/R'. Draw a circuit diagram to show two resistors R1 and R2 connected in parallel along with a battery, key, ammeter voltmeter.
- A number of bulbs are to be connected to a single source. Will they provide more illumination when connected in parallel or in series? Give reasons to justify your answer and also list two advantages of this type of arrangement.
- An electric bulb is rated at 60 W to 240 V. Calculate its resistance. If the voltage drops to192 V, calculate the power consumed and the current drawn by the bulb. (Assume that the resistance of the bulb remains changed).
- An electric circuit consisting of 0.5 m long nichrome wire XY an ammeter, a voltmeter four cells of 1.5 V each and a plug key was set up. Draw a diagram of this circuit in the ON position.
- .Electric resistivities of some substances, in ohm-meter, at 200 C are given as follows:
(a)Silver - 1.60 x 10-8
(b) Copper - 1.62 x 10-8
(c) Tungsten - 5.2 x 10-8
(d) Mercury - 1.60 x 10-8
(e) Iron - 10 x 10-8 .
(f) Nichrome - 10 x 10-6
(a) Out of the silver and copper, which is a better conductor of electric current and why?
(b) Which substance is preferred to be used for electric transmission lines?
(c) Name the material that you would advise to be used in the heater elements of the electric heating device and why? - (a) State one difference between kilowatt and kilowatt-hour. Express 1 kWh in joules.
(b) A bulb is rated 5 V; 500 mA. Calculate the rated power and resistance of the bulb when it glows. - Calculate the amount of heat generated when 7200 coulombs of charge are transferred in one hour through a potential difference of 50 V.
- Define electric power. An electric motor is rated at 2kW. Calculate the cost of using it for 2 hrs. daily for the month of September if each unit costs Rs. 6.
- Two devices of rating 44 W, 200 V and 11 W, 220 V are connected in series. The combination is connected across a 440-volt mains. The fuse of which of the two devices is likely to burn when the switch is on. Justify your answer.
- Five resistors are connected in a circuit as shown. Find the ammeter reading when the circuit is closed.
- How many resistors of 88Ω are connected in parallel to carry 10-ampere current on a 224V line?
- Derive an expression for the combination of two resistance connected in series.
- A wire of length l and area of cross-section A was drawn into a wire of double its length by melting it. If its original Resistivity and resistance wire p and R respectively, what will be its new resistivity and resistance?
- A 400 W refrigerator operates for 16 hour 5 per day. Calculate the cost to operate it for 30 days at Rs 3.40 kWh.
- (a) A wire of resistivity p is stretched to double its length of new resistivity. Give the reason for your answer.
(b) Draw a schematic diagram of a circuit consists of a battery of three cells 2 volts each, 5Ω resistor, 8Ω resistor, and 12Ω resistor and a plug key all connected in series.
(c) Two wires, one of Copper and other of Manganese have equal lengths and equal resistances which is thicker. (Given that resistivity of manganese is lower than that of copper). - (a) What is meant by the statement that the resistance of a wire is 1Ω?
(b)Two identical resistors each of resistance 12Ω are connected
(i) in series and (ii) in parallel in turn to a battery of 6 volts.
Calculate the ratio of power consumed in the combination of resistors in the two cases.
(c) What combination is used for connecting in the circuit to measure the potential difference across two points? - (a) Derive an expression for the equivalent resistance of three resistors R1 R2 and R3 connected in series.
(b) The fuse of 3A, 5A, and 10A are available. Calculate and select the fuse for operating electric iron of 1kW power at 220 V line. - (a)Explain the term: Heating effect of electric current.
(b) Derive an expression for the heat produced by electric current and state joules law.
(c) Explain why an inert gas like Argon is filled in bulbs. - (a)What is meant by potential difference? State its SI unit.
(b) Name a device that helps to maintain a potential difference across a conductor
(c) Calculate (i) the highest, (ii) the lowest resistance that can be obtained by the combination of four coils of resistance 4Ω, 8 Ω, 12Ω and 24Ω. - Two conductors A and B of resistance 5Ω and 10Ω respectively are the first joint in parallel and then and series. In case the voltage applied is 20 volt.
(a) Draw the circuit diagram to show the combination of these conductors in each case.
(b) In which combination will the voltage across the conductor A and B be the same
(c) In which arrangement will the current through A and B be the same.
(d) Calculate the equivalent resistance for each arrangement. - Why does the connecting rod of an electric heater not glow while the heating element does?
- The resistance of the conductor is R. If its length is doubled, then its new resistance will be (a)R (b) 2R (c) 4R (d) 8R.
- Two wires A and B are of equal length, different cross-sectional areas and made of the same metal.
(a) (i) Name the property which is the same for both the wires,
(ii) Name the property which is different for both the wires.(b) If the resistance of wire A is four times the resistance of wire B, Calculate:
(i) The ratio of the cross-sectional areas of the wires and
(ii) The ratio of the radii of the wire. - Two resistors of resistance R and 2R are connected in parallel in an electric circuit. Calculate the ratio of the electric power consumed by R and 2R?
- Should the heating element of an electric iron be made of iron, silver or nichrome wire? Justify giving three reasons?
- (a) Define the electric resistance of a conductor?
(b)A wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved. How will its
(i) resistance change (ii) resistivity change? - Two metallic wires A and B are connected in second wire A has length l and radius r, while wire B has length 2l and radius 2r. Find the ratio of the total resistance of series combination and the resistance of wire A, if both the wires are of the same material?
- How does the use of fuse wire protect electrical appliances?
- Calculate the resistance of an electric bulb which allows a 10A current when connected to a 220V power source?
- The resistivity of a metallic wire depends on:
(a) its length (b) its shape (c) its thickness (d) nature of the material. - Which of the following expressions does not represent the electric power in the circuit?
(a) VI (b) I2/R (c) V2/R (d) I2 R. - A metallic conductor has loosely bound electrons called free electrons. The metallic conductor is :
(a) negatively charged
(b) positively charged
(c) neutral
(d) Either positively charged or negatively charged.
Find the equivalent resistance across the two ends A and B of this circuit. - An electric circuit consisting of 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5V each and a plug key was set up. Draw a diagram of this circuit in the ON position. The following graphs were plotted between the value of the potential difference (V) and electric current (I). State the conclusion that you draw about the relation between V and I from this graph.
- (a) Derive an expression for Joule's law of heating.
(b) Give two examples for applications of heating effect of electric current.
(c) 100 J of heat is produced each second in a 4Ω resistor. Find the potential difference across the resistor. - (a) What is the total resistance of resistors each of resistance R connected in:
(i) Series (ii) Parallel.
(b) Calculate the resultant resistance 3Ω, 4 Ω, and 12Ω connected in parallel. - State in brief the meaning of a variable resistor draw a circuit diagram to illustrate its function especially in the study of variation in current with a potential difference across a resistor.
(a) Calculate the resistance of the wire using the graph.
(b) How many 176Ω resistors in parallel are required to carry 5A on a 220 V line?
(c) Define electric power. Derive the relation between Power, potential difference and resistance. - (a) What is meant by the statement that the resistance of a wire is 1Ω?
(b) Two identical resistors each of resistance 12Ω are connected in series and parallel intern to a battery of 6 volts. Calculate the ratio of power consumed in the combinations of resistors in the two cases.
(c) What combination is used for connecting in the circuit to measure the potential difference across two points? - (a) Derive an expression for the equivalent resistance of three resistors R1 R2 R3 connected in series.
(b) The fuse of 3A 5A and 10 A are available. Calculate and select the fuse for operating electric iron of 1 KW power at 220 V line. - Find out the following in the electric circuit given in the figure.
(a) The effective resistance of two 8Ω resistors in the combination.
(b) Current flowing through 4Ω resistor
(c) Potential difference across 4Ω resistor (d) Power dissipated in 4Ω resistor
(d) Difference in the reading of ammeter A1 and A2 if any. - (a) Two students perform experiments on two given resistors R1 and R2 and Plot the following v - I graph if R1 > R 2, which of the two diagrams correctly represents the situation on the plotted curves. Justify your answer.
(b) An electric lamp of 20Ω and a conductor of 6Ω are connected in parallel to a 12-volt battery. Calculate (i) total resistance (ii) total current in the circuit. (iii) The potential difference across the conductor. - (a) How will you convert a given set of resistors so that the equivalent resistance is increased? Give a reason for your answer.
(b) In the above circuit diagram Calculate:
(i) the value of current through each resistor.
(ii) the total current in the circuit.
(iii) the total effective resistance of the circuit.
- (a) Two identical resistors each of resistance 10Ω are connected in(i)Series (ii) parallel in turn to a battery of 6 V. Calculate the ratio of power consumed by the combinations of resistors in the two cases.
(b) List two factors on which the resistance of a conductor depends.
(c) Write a difference between an ammeter and a voltmeter.
- Draw a circuit diagram for a circuit consisting of a battery of five cells of 2 voles each, a 5Ω resistor, 10Ω resistor, and a 15Ω resistor and ammeter and a plug key all connected in series. Also, connect a voltmeter to record the potential difference across the 15Ω resistor and calculate:
(a) The electric current passing through the above circuit and
(b) The potential difference across 5Ω resistor when the key is closed. - (a) State ohm’s law?
(b) The value of (I) current flowing through a conductor for the corresponding valves of (V) potential difference are given below
I (Ampere) 0.5 1.0 1.5 2.5 3
V(Volt) 1 2 3 4.5 5
Plot a graph between V and I and also calculate resistance. - I. Amongst iron, silver, Nichrome, tungsten, copper which metal alloy should be used to make the (a) Heating element of the electric geyser.
- An electric lamp of resistance 20 Ω and a resistor of 4 Ω are connected to a 6-volt battery as shown in the circuit diagram.
Calculate
(a) The total resistance of the circuit
(b) Current through the circuit and
(c) The potential difference across the electric lamp and the resistor.
(b) The filament of incandescent bulbs.II. An electric iron has a rating of 750 W,220V. Calculate.
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