QUESTION BANK CHAPTER: ELECTRICITY MULTIPLE CHOICE QUESTIONS (THEORY BASED) 1.
2.
The rate of flow of an electric charge is known as: (a) Electric power (b) electric current (c) resistance The relation between potential difference (V) and current (I) is: (a) 𝑉 ∝
3.
(d) electric potential
1 𝐼
(b) 𝑉 ∝ 𝐼 2
(c) 𝑉 2 ∝ 𝐼
(d) 𝑉 ∝ 𝐼
Which one of the following statement correctly describes the resistance of a given conductor? (a) Resistance is the heat energy possessed by the conductor. (b) Resistance is the obstruction offered by material of conductor to the passage of electric current. (c) Resistance is the ability of a conductor to allow flow of charges through it. (d) Resistance is property of a conductor which maintains a balance between electric current and potential difference and keeps the V-I graph of the given conductor always a straight line.
4.
A battery of 12V is connected in series with resisters of 0.2 ohm, 0.3 ohm, 0.4 ohm, 0.1 ohm and 11 ohm. How much current would flow through the 0.3 ohm resister? (a) 40 A
5.
7.
(d) 1 A
(b) temperature
(c) density
(d) area of cross-section
Heating of a current carrying conductor is due to (a) Loss of kinetic energy by atoms
(b) loss of kinetic energy by electrons
(c) Attraction between electrons and protons
(d) repulsion between electrons; protons
What is the correct relationship between mA and A? (a) 1000 mA = 1 A
8.
(c) 0.025 A
Among which of the following resistance does not depend: (a) Length of the wire
6.
(b) 24 A
(b) 10000 mA = 1 A
(c) 1 A = 1/1000 mA
(d) 1 mA = 1/100 A
Which one of the following statement is correct? (a) The direction of current in a circuit is assumed to be opposite to the direction of motion of free electrons. (b) In the series combination of resistors, the potential difference has the same value across any two points of the circuit (c) The series arrangement should be used for household circuits (d) Voltmeter is always connected in series between which the potential difference is to be measured.
9.
In an electric circuit three incandescent bulbs A, B and C of rating 40W, 220 V; 60W, 220 V and 100W, 220V respectively are connected in PARALLEL to an electric source. Which one of the following is likely to happen regarding their brightness? (a) Brightness of bulb A is maximum.
(b) Brightness of bulb B is maximum.
(c) Brightness of bulb C is maximum.
(d) Brightness of all bulbs will be same.
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10.
11.
12.
In an electric circuit three incandescent bulbs A, B and C of rating 40W, 220 V; 60W, 220 V and 100W, 220V respectively are connected in SERIES to an electric source. Which one of the following is likely to happen regarding their brightness? (a) Brightness of bulb A is maximum.
(b) Brightness of bulb B is maximum.
(c) Brightness of bulb C is maximum.
(d) Brightness of all bulbs will be same
Three resistors A, B and C of resistance 1Ω, 10Ω, and 100Ω respectively are connected in parallel. The approximate equivalent resistance of the combination would be (a) More than 100 Ω
(b) more than 10 Ω but less than 100 Ω
(c) More than 1 Ω but less than 10 Ω
(d) less than 1 Ω
What makes the electric charge to flow in a conductor? (a) Electric current in the conductor
(b) potential difference across the conductor
(c) It flows because of Ohm’s law
(d) presence of conducting path
VERY SHORT ANSWER QUESTIONS (1 MARK) 1.
What is meant by saying that potential difference between two points is 1V?
2.
Name and state the law which relates the current in a conductor to the potential difference across a conductor.
3.
Name the device used to change resistance in a circuit to regulate current without changing the voltage source.
4.
State any one property and one use of nichrome.
5.
The V–I graph is a straight line that passes through the origin of the graph. What do you conclude from this observation?
6.
List two ways to increase the current drawn by a circuit?
7.
Why does the cord of an electric heater not glow while the heating element does? (HOTS)
8.
How can three resistors of resistances 2Ω, 3Ω and 6Ω be connected to give a total resistance of 4Ω? (HOTS)
9.
3 light bulbs are connected in parallel to a power supply. What will be the effect on the rest of the bulbs when one burns out? Will the remainder glow brighter or dimmer? What will be the effect on the source? (HOTS)
10.
What is a short circuit? Give two ways to protect against short circuits.
SHORT ANSWER QUESTIONS (2 MARKS) 1.
A wire of resistance 10ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the end of any diameter of the circle? (HOTS)
2.
Two lamps rated 100W, 220V and 120W, 220V are connected in parallel to 220V supply. Calculate the total current through the circuit.
3.
A bulb is rated at 220V- 100W. What is its resistance? Five such bulbs burn for 4 hrs. What is the energy consumed? Calculate the cost if the rate is Rs. 5 per unit?
4.
Give two special properties of alloy nichrome which makes it suitable for making heating element in devices such as electric iron, heater.
5.
Give two special properties of Tungsten which makes it suitable for making filament in an incandescent lamp.
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6.
Give two properties of copper which makes it suitable for electrical transmission.
7.
Which will offer more resistance a 50W lamp or 25W lamp bulb and how many times?
8.
Which effect of current is responsible for the glow of an electric bulb? State the law relating the effect. Also derive the expression for the same.
9.
A wire of resistance 20 Ω is stretched to double its length. What will be its new (i) resistivity (ii) resistance? (HOTS)
10.
Calculate the work done in moving a charge of 5 Coulombs from a point at a potential of 210 Volts to another point at 240 Volts.
SHORT ANSWER QUESTIONS (3 MARKS) 1.
On what factors does the resistance of a conductor depend?
2.
Find resistance between A and B in following network
3.
A wire of given material having length l and area of cross-section A has a resistance of 4 Ω. What would be the resistance of another wire of the same material having: (a) Length l/2 and area of cross-section 2A? (b) Length 2l and area of cross-section A/2? (c) Length 2l and area of cross-section 2A?
(HOTS)
4.
A torch bulb when cold has 1Ω resistance. It draws a current of 0.3 Ampere when glowing from a source of 3 V. Calculate the resistance of the bulb when glowing and explain the reason for the difference in resistance. (HOTS)
5.
There is a current of 0.50 A through an incandescent lamp for 5.0 min, with a voltage of 115 V. How much energy does the current transfer to the lamp? What is the power rating of the lamp?
6.
An electric drill operates at a potential difference of 120V and draws a current of 6.0 mA. If it takes 40 s for the drill to make a hole in a piece of wood, how much energy is used by the drill?
7.
A motor draws a current of 2.0 A for 20.0 sec in order to lift a small mass of 500 g. If the motor does a total of 9.6 kJ of work calculate the voltage drop across the motor.
8.
(a) Describe the difference between current in a series circuit and current in a parallel circuit. (b) Describe the difference between voltage in a series circuit and voltage in a parallel circuit. (c) Do resistors in parallel increase or decrease total resistance?
9.
The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below – I (amperes)
0.5
1.0
2.0
3.0
4.0
V (volts)
1.6
3.4
6.7
10.2
13.2
Plot a graph between V and I and calculate the resistance of that resistor. Please visit www.physics10aps.blogspot.com for more practice papers and online tests.
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10.
Ajay, Vijay and Neha were constructing an electric circuit in the physics lab. They put 15 light bulbs each of rating 60W, 220V in parallel to a 220 V power supply. The wires used in the circuit had a maximum current carrying capacity of 3A. Ajay put the voltmeter in parallel to the one of the light bulb. Vijay add the ammeter in the circuit in series with one of the light bulb. Neha put an electric fuse in series with the whole circuit while the others regarding this as a useless device and were making fun of Neha. (Value Based) (a) What would have happen when the circuit is switched ON? (b) What values were exhibited by Neha? (c) What would be the reading of ammeter and voltmeter if 5 bulbs were removed from the circuit? What would be the total current drawn from the circuit?
LONG ANSWER QUESTIONS (5 MARKS) 1.
Draw a schematic diagram of the following circuit: One power source and a resistor are connected in series with a combination of 3 light bulbs connected in parallel with each other. Include a fuse, 4 switches, a voltmeter, and an ammeter. The fuse should protect the whole circuit, one switch should shut off the whole circuit and the other switches should control the individual bulbs. The ammeter should read current drawn from power source and the voltmeter the voltage of the resistor. Describe the effect on the rest of the bulbs in the above problem when one burns out. Will the remainder glow brighter or dimmer? What will be the effect on the source?
2.
(i) State the formula showing how the current I in a conductor varies when the potential difference V applied across it is increased stepwise. (ii) Show this relationship on a schematic graph. (iii) Calculate the resistance of a conductor if the current flowing it is 0.2 A, when the applied potential difference is 0.8V
3.
(a) Prove that expressions VIt, I2Rt and V2t/R are equal. (b) Compare the power used in the 2Ω resistor in each of the following circuits: (i) a 6 V battery in series with 1Ω and 2Ω resistors, and (ii) a 6 V battery in parallel with 12 Ω and 2Ω resistors. (Ans. 8W, 18 W).
4.
A set of 6 identical motors are connected in series to a 120 V source drawing 1.0 A of current. Find: a) R total b) R of each motor (C) Current through each motor c) Voltage drop across each load. (Ans. 120Ω, 20Ω and 20 V)
5.
A set of 6 identical motors are connected in parallel to a 150 V source drawing 1.2 A of current. Find: a) R total b) R of each motor c) Current through each motor d) Voltage drop across each load. (Ans. 125Ω, 750Ω, 0.2 A and 150 V)
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CHAPTER: MAGNETISM MULTIPLE CHOICE QUESTIONS (THEORY BASED) 1.
Choose the incorrect statement from the following regarding magnetic lines of field (a) The direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points (b) Magnetic field lines are closed curves (c) If magnetic field lines are parallel and equidistant, they represent zero field strength (d) Relative strength of magnetic field is shown by the degree of closeness of the field lines
2.
If the key in the arrangement is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are
(a) Concentric circles (b) elliptical in shape (c) Straight lines parallel to each other (d) Concentric circles near the point O but of elliptical shapes as we go away from it 3.
A circular loop placed in a plane perpendicular to the plane of paper carries a current when the key is ON. The current as seen from points A and B (in the plane of paper and on the axis of the coil) is anti clockwise and clockwise respectively. The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the face close to
(a) A (c) A if the current is small and B if the current is large (d) B if the current is small and A if the current is large 4.
(b) B
For a current in a long straight solenoid N- and S-poles are created at the two ends. Among the following statements, the incorrect statement is (a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid (b) The strong magnetic field produced inside the solenoid can be used to magnetize a piece of magnetic material like soft iron, when placed inside the coil (c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet (d) The N- and S-poles exchange position when the direction of current through the solenoid is reversed
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5.
A uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure. In the field an electron and a proton move as shown. The electron and the proton experience
(a) Forces both pointing into the plane of paper (b) Forces both pointing out of the plane of paper (c) Forces pointing into the plane of paper and out of the plane of paper, respectively (d) Force pointing opposite and along the direction of the uniform magnetic field respectively 6.
In the arrangement shown in there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted. Then the key is inserted and later removed. Then
(a) The deflection in the galvanometer remains zero throughout (b) There is a momentary deflection in the galvanometer but it dies out shortly and there is no effect when the key is removed (c) There are momentary galvanometer deflections that die out shortly; the deflections are in the same direction (d) There are momentary galvanometer deflections that die out shortly; the deflections are in opposite directions 7.
Choose the incorrect statement (a) Fleming’s right-hand rule is a simple rule to know the direction of induced current (b) The right-hand thumb rule is used to find the direction of magnetic fields due to current carrying conductors (c) The difference between the direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically (d) In India, the AC changes direction after every 150 second
8.
A constant current flows in a horizontal wire in the plane of the paper from east to west as shown in figure. The direction of magnetic field at a point will be north to South (a) Directly above the wire (b) Directly below the wire (c) At a point located in the plane of the paper, on the north side of the wire (d) At a point located in the plane of the paper, on the south side of the wire
9.
The strength of magnetic field inside a long current carrying straight solenoid (a) More at the ends than at the centre (b) minimum in the middle (c) Same at all points (d) found to increase from one end to the other
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is
10.
The most important safety method used for protecting home appliances from short circuiting or overloading is (a) Earthing (b) use of fuse (c) use of stabilizers (d) use of electric meter
11.
A fuse is rated at 8 A, it means: (a) It will not work if current is less than 8 A. (c) It will work only if current is 8 A.
(b) It has a resistance of 8 ohm. (d) It will burn if current exceeds 8 A.
VERY SHORT ANSWER QUESTIONS (1 MARK) 1.
Why does a compass needle got deflected when brought near a bar magnet?
2.
The magnetic field in a given region is uniform. Draw a diagram to represent it.
3.
Name some sources of direct current.
4.
Which sources produces alternating current?
5.
Name two safety measures commonly used in electric circuit and appliances.
6.
What precautions should be taken to avoid the overloading of domestic electric circuit?
7.
When is the force experienced by a current-carrying conductor placed in a magnetic field largest?
8.
Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason. (HOTS)
9.
A magnetic compass shows a deflection when placed near a current carrying wire. How will the deflection of the compass get affected if the current in the wire is increased? Support your answer with reason. (HOTS)
10.
How can you locate a current-carrying wire concealed in a wall? (HOTS)
SHORT ANSWER QUESTIONS (2 MARKS) 1.
List any two properties of magnetic field lines.
2.
Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of magnetic field inside and outside the loop. (HOTS)
3.
Why don’t two magnetic field lines intersect each other?
4.
Explain any two different ways to induce current in a coil.
5
State Fleming’s left hand rule.
6.
State Fleming’s right hand rule.
7.
State right hand thumb rule.
8.
Define electromagnetic induction.
9.
(a) What is the effect of inserting a soft iron core inside a current-carrying solenoid?
(HOTS)
(HOTS)
(b) What is this arrangement known as? 10.
State two characteristics of electric fuse wire.
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SHORT ANSWER QUESTIONS (3 MARKS) 1.
State three factors on which the magnitude of force on a current carrying –conductor placed in a magnetic field depends. Can this force be zero for some position of the conductor?
2.
Draw the magnetic field lines around a straight conductor carrying current.
3.
Draw the magnetic field lines due to a current-carrying circular wire.
4.
What is solenoid? Draw the magnetic field lines due to a current carrying solenoid. Compare the magnetic field produced by a bar magnet and a solenoid?
5.
State the rule to determine the direction of a (i) Magnetic field produced around a straight conductor carrying current. (ii) Force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it. (iii) Current induced in a coil due to its rotation in a magnetic field.
6.
(a) An electric oven of a 2kW power rating is operated in a domestic circuit (220 V) that has a current rating of 5A. What result do you expect? Explain. (b) Why should a fuse with defined rating not be replaced by one with a larger rating?
7.
Imagine you are sitting in your physics lab with your back to one wall. A wire running horizontally from back wall towards the front wall is deflected by a strong magnetic field to your right side when the circuit is switched ON. What is the direction of the magnetic field? State the rule you used to find the direction of magnetic field. (HOTS)
8.
It is established that an electric current through a metallic conductor produces a magnetic field around it. Is there a similar magnetic field produced around a thin beam of moving (i) alpha particles, (ii) neutrons? Justify your answer. (HOTS)
9.
AB is a current carrying conductor in the plane of the paper as shown in Figure. What are the directions of magnetic fields produced by it at points P and Q? Given r1 > r2, where will the strength of the magnetic field be larger? (HOTS) Shubham’s family purchased a new house. His father decided to replace the old domestic electric wiring with the new thicker wires to carry the load of Air Conditioners (ACs). Shubam observed that the electrician is not following the colour code of domestic electric circuit. He is using all possible colours of wires available to him like green, yellow, blue, black, red and violet. Shubham asked him to stop the work immediately and ordered him to remove all the wires and start from the beginning with the correct colour code of wires. (a) What might have happened if the electrician doesn’t follow the correct colour code? (b) In India what colour code do we follow for domestic electric circuit? (c) What values were exhibited by Shubham? (d) What values were exhibited by Shubham’s father? (Value Based)
10.
LONG ANSWER QUESTIONS (5 MARKS) 1.
A coil of insulated copper wire is connected to a galvanometer. What would happen if: (i) a bar magnet is pushed into the coil. (ii) a bar magnet is withdrawn from inside the coil. (iii) a bar magnet is held stationary inside the coil. (iv) Bar magnet and coil but moves with the same speed in the same direction. (v) The coil is moved towards the magnet and the magnet is kept stationary.
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2.
Draw an appropriate schematic diagram showing common domestic circuits and discuss the importance of fuse. Why is it that a burnt out fuse should be replaced by another fuse of identical rating?
3.
Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases.
4.
(a) What is the earth wire? What is the function of earth wire? Why is it necessary to earth the metallic appliances? (b) When does an electric short-circuit occur? (d) What is over loading?
5.
Observe the given figure and answer the following.
(a)
What is the name given to two coils shown above?
(b)
What will happen when the key is inserted in the first coil?
(c)
What will happen when the key is removed from the first coil?
(d)
What will happen to the deflection of galvanometer needle if the number of turns in the first coil is increased?
(e)
Imagine you are conducting the above experiment and your friend visits you. Assume at that moment the circuit was already switched ON. Will your friend observe any deflection in the galvanometer?
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PRACTICAL BASED QUESTIONS LIST OF PRACTICALS (SA1) 1. To study the dependence of potential difference (V) across a resistor on the current (I) passing
through it and determine its resistance. Also plot a graph between V and I. 2.
To determine the equivalent resistance of two resistors when connected in series.
3.
To determine the equivalent resistance of two resistors when connected in parallel.
MULTIPLE CHOICE QUESTIONS (PRACTICAL BASED)
1.
2.
A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with the resistances R1, R2 and R3 respectively. Which of the following is true? (a)
R1 > R2 > R3
(b)
R1 = R2 = R3
(c)
R3 > R2 > R1
(d)
R2 > R3 > R1
Using the circuit given below current and potential difference were measured and these values were plotted on a graph. Which one of the following graphs most correctly shows the dependence between current and potential difference?
(a) A
3.
(b) B
(c) C
(d) D
In a voltmeter, there are 20 divisions between the 0 mark and 0.5 V mark. The least count of the voltmeter is (a) 0.020 V
(b) 0.050 V
(c) 0.025 V
(d) 0.250 V
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4.
The voltmeter, ammeter and resistance in the circuit shown have been checked to be correct. On plugging the key, the ammeter reads 0.9 A, but the voltmeter reads zero. This could be because
(a) The voltmeter is incorrectly placed in the circuit.
(b) The wires joined to the voltmeter terminals are loose
(c) The least count of the voltmeter is too high. (d) The range of the voltmeter is more than twice the battery voltage 5.
Identify the circuit in which the electrical components have properly connected.
(a) B
(b) A
(c) D
(d) C
6. Four students A, B, C and D set up their circuits for studying the dependence of the current through a resistor on the potential difference across it, as follows. The correct circuit is
(a) C
(b) D
(c) A
(d) B
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Page 11 of 16
7.
In an experiment to study the dependence of current on potential difference across a resistor, a student obtained the graph as shown in the diagram. The value of resistance of the resistor is
(a) 1 Ω
8.
9.
(b) 10 Ω
(c) 100 Ω
(d) 0.1Ω
The plot correctly showing the dependence of the current I on the potential difference V across a resistor R is (a) A
(b) B
(c) C
(d) D
To the terminals marked as X and Y in the given circuit, three students connect 4 cells of voltage 1.5 V each in three manners shown below: The readings of the voltmeter, for the three students, are likely to be (nearly)
(a) V1 = 6.0 V; V2 = 1.5 V; V3 = 3.0 V
(b) V1 = 3.0 V; V2 = 6.0 V; V3 = 1.5 V
(c) V1 = 6.0 V; V2 = 3.0 V ; V3 = 0 V
(d) V1 = 3.0 V; V2 = 1.5 V; V3 = 6.0 V
10. In an experiment to study dependence of current I on the potential difference across a given resistor, students kept the plug key in the circuit closed for time t1 and then open for time t2. The times t1 and t2 for students P,Q ,R and S are given in the table below. The best choice of open and closed times is that of student: (a) P
(b) Q
(c) R
(d) S
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11.
On plugging the key K, the ammeter A reads zero. This is because (a) the ammeter connection is wrong. (b) the range of ammeter is inappropriate (c) least count is too small (d) least count is too big
12.
The positive and negative terminals markings are shown in a circuit by the following figures. Which of the figures will give correct connections?
(a) D only 13.
(c) A and B both
(d) B and D both
The positive and negative terminal markings are shown in a circuit by the following figures. Which of the figures will give correct connections?
(a) C and B both (c) A only
14.
(b) A and C both
(b) D and A both (d) B and D both
In the above circuit, two ammeters are connected through two resistors in series whose pointer shows deflection. Then the reading of the ammeter A1 and A2 will be such that (a) A1, A2 = 0 (b) A1 > A2 (c) A1 < A2 (d) A1 = A2
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15.
In the above circuit, two voltmeters are connected through the resistors, whose pointer shows deflection. Then the reading of the voltmeters V1 and V2 will be such that (a) V1, V2 = 0 (b) V1 > V2 (c) V1 < V2 (d) V1 = V2
16.
In Circuit A: Ammeter reads current I1 and the voltmeter reads voltage V1. In Circuit B: ammeter reads current I2 and voltmeter reads voltage V2 The relationship between the readings is
(a) I1 = I2, V2 = V1 (b) I2 > I1, V1 = V2 (c) I1 = I2, V2 > V1 (d) I1 < I2, V2 = V1
17.
18.
The relation between the ammeter and voltmeter readings in circuit A and B is
(a) I1 = I2, V1 < V2
(b) I1 > I2, V1 > V2
(c) I1 < I2, V1 = V2
(d) I1 > I2, V1 = V2
A student connects a circuit to study Ohm’s law using a resistor of 3 ohm and a battery eliminator of 6 V. Which of the ammeter should be chosen to read the value of current for this circuit, if the ammeters available in the laboratory have the following ranges? (a) 0 – 200 mA
19.
(c) 0 – 1 A
(d) 0 – 2 A
An ammeter has a range of (0-3A) amperes and there are 30 divisions on its scale. What is its least count? (a) 1.0 A
20.
(b) 0 – 100 mA
(b) 0.001 A
(c) 0.1 A
(d) 0.01 A
Which of the following devices would you use of maintain potential difference between two points of a conductor?
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21.
In a milliammeter, there are 20 divisions between 400 mA and 500 mA mark. The least count of the milliammeter is (a) 0.5 mA
22.
(b) 5 mA
(c) 10 mA
(d) 50 mA
Using the following measuring instruments, the best pair made for carrying out experiment to determine resistance of a resistor of nearly 30 ohm is : Milliammeter (A1) : Range 0 – 100 mA, least count 20 mA Milliammeter (A2) : Range 0 – 500 mA, least count 5 mA Voltmeter (V1) : Range 0 – 3V and least count 0.05 V Voltmeter (V2) : Range 0 – 2V and least count 0.04 V (a) A1 and V1
23.
(b) A1 and V2
(c) A2 and V2
(d) A2 and V1
Which one of the following precaution is NOT to be taken while conducting the experiment to determine the equivalent resistance of two resistors connected in series? (a) Get the circuit diagram checked by your teacher before passing current. (b) Connect +ve terminal of the ammeter to the +ve terminal of the battery. (c) Wait atleast for 30 seconds after closing the key. (d) Take care that the battery is not short circuited.
24.
A voltmeter has a least count of 0.05 volt. While doing Ohm’s law experiment, astudent observed that the pointer of the voltmeter coincides with the 15th division. The observed reading is : (a) 0.75 V
25.
(b) 0.075 V
(c) 7.5 V
(d) 75 V
You are given four voltmeters of given ranges. The correct choice of voltmeter for doing the experiment with the battery of 4.5 V is: (a) Voltmeter with range of 0 – 1V
(b) Voltmeter with range of 0 – 3 V
(c) Voltmeter with range of 0 – 4 V
(d) Voltmeter with range of 0 – 5V
26.
The reading of the voltmeter and the ammeter did not change on moving the sliding contact of rheostat. The possible reason was: (a) both the lower terminals of rheostat were connected. (b) one upper terminal and other lower terminal was connected. (c) the wire of the rheostat was broken somewhere. (d) sliding contact did not touch the wire of the rheostat.
27.
In the experiment to verify ohms law some of the precautions taken by a student after choosing an ammeter and voltmeter of range 3A and 3V respectively were described to the teacher. (A) Connect rheostat by using any of its two terminals. (B) Use voltage supply of 2V from the battery eliminator. (C) The ‘key’ in the circuit, once plugged in, should not be taken out till all the observations have been completed. (D) Use long and thin copper wires for making connections. Teacher found the steps to be incorrect: (a) A, B and C (b) B, C and D (c) A, C and D (d) A, B and D
28.
Two resistors of resistances 2 Ω and 4 Ω when connected to a battery will have
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(a) Same current flowing through them but different potential difference across them when connected in parallel. (b) Same current flowing through them but different potential difference across them when connected in series. (c) Same potential difference across them but different current through them when connected in series. (d) Different potential difference across them and different current flowing through them when connected in parallel. 29.
A student did the experiment to find the equivalent resistance, of two given resistors, R1 and R2, first when they are connected in series and next when they are connected in parallel. The two valves of the equivalent resistance obtained by him were Rs and Rp respectively. He would find that (a) RS > RP (b) RP > RS (c) RP = RS (d) RS = RP, only when R1 = R2
30.
A student draws the following circuit diagram for the experiment on studying the dependence of current (I) on p.d. (V) across a resistor. The parts labeled X, Y and Z, in this diagram are, respectively, (a) a resistor, a voltmeter and a milliameter. (b) a voltmeter, a resistor and a milliameter. (c) a millimeter, a resistor and a voltmeter. (d) a resistor, a milliameters and a voltmeter.
PRACTICAL BASED REASONING QUESTIONS 1.
Shyam picked four resistors of resistances 4 Ω, 8 Ω, 12Ω and 24 Ω from his physics lab. His friend Uday challenged him to connect them to get the maximum and minimum resistance from the arrangement. How Shyam would connect these resistances?
2.
Gita connected three resistors each of resistance 4Ω in the form of equilateral triangle. She asked her friend whether it is a series or parallel combination and what is the effective resistance between two corners? Being a good friend of Gita how would you solve her problem?
3.
Joginder cuts a 90 Ω resistance wire into three equal parts and connected them in parallel. What is the equivalent resistance of the combination?
4.
Vijay sets up the circuit using a resistor of unknown resistance, ammeter, voltmeter, battery and a key. On switching ‘ON’ the circuit, the ammeter reads 0.2A and voltmeter reads 0.8 V. What is the resistance of the resistor that Vijay picked up?
5.
How many 40W bulbs can be safely connected in a parallel circuit which is drawing current through a 5 A fuse from a 220 V supply?
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