Question 32: (b) becomes double (c) Current will not flow through voltmeter as the key is open. (b) The -ve of voltmeter should be connected to +ve of ammeter and R( and R, should be connected in parallel. (a) 10 (c) Battery In an electric circuit the key should be kept off to avoid: How many electrons are present in 1 coulomb? It is also used to stop the current through circuit when it is open. Define electric current. Which of the following set-up is correct for the verification of Ohm’s law. To verify ohm's law, one galvanometer is used as ammeter and other galvanometer as voltmeter. Question 1: Its SI units is ohm(Ω). S.I. The pointers of the ammeter and voltmeter should be at zero mark when no current flows through the circuit. The ammeter connected in a circuit reads 0.01 A when battery is switched off. Connect the circuit as shown in figure, using one cell. For the circuits shown in figures I and II, the ammeter readings would be: (b) ammeter The phase difference between displacement and acceleration of a particle in a simple harmonic motion is: A cylinder contains hydrogen gas at pressure of Each and every wire that may be a very good conductor of electricity will certainly offer some resistance to the flow of electrons. The resistance of the lead wires is $6 \, \Omega$. Voltmeter should have high resistance (connected in parallel) ammeter should have low resistance (connected in series) given: R1 --- high resistance, R2 ---- low resistance. One coulomb is the amount of charge present on 6.25 x 1018 electrons. Least count of ammeter and voltmeter. He would observe Potential difference In an electric circuit carrying current, the work done to move a unit charge from one point to the other is called potential difference. Plot a graph of voltmeter reading and current reading. The nature of resistor, i.e., material of a conductor. Calculate Power, Current, Voltage or Resistance. Аnswer: The only correct statement for the following electric circuit is 2. (a) potential difference If the known resistor is replaced by the nichrome wire than the current will decrease and the potential difference will decrease. Question 7: In National 5 Physics calculate the resistance for combinations of resistors in series and parallel. Question 15: CBSE Class 10 Science Practicals Lab Manual MCQ Аnswers: Physics Lab Manual CBSE Class 10 Scoring Key With Explanation, NCERT Solutions for Class 6 Social Science History Chapter 2 On the Trial of the Earliest People. 5. Set up your circuit with the power supply OFF and the output voltage turned DOWN TO ZERO. The slope of this straight line graph gives: Question 12: Аnswer: What is the nature of graph obtained for V and I? (d) In circuit I, the current 5V/5 ohm = 1 A. (d) 0 V in circuit I and 2 V in circuit II. (a) We must keep the circuit closed for a relatively shorter time and open for a relatively longer time. Click hereto get an answer to your question ️ Express which of the following setups can be used to verify Ohm's law : - (d) variable resistance. What is the formula used to calculate the resistivity of a given wire? The area of cross-section of the resistor. To calculate resistivity. Аnswer: (c) positive error (a) (d) in both the set-ups. (a) P (b) Q (c) R (d) S. More Resources CBSE Class 10 Lab Manual Practical Skills: Kerala Syllabus 9th Standard Physics Solutions Guide, Kerala Syllabus 9th Standard Biology Solutions Guide, NCERT Class 10 Science Lab Manual – Ohm’s Law, CBSE Class 10 Science Lab Manual Practical Based Questions, Science lab manual class 10 NCERT Lab Manual Questions, Science lab activities for class 10 CBSE Multiple Choice Questions (MCQs). (b) ammeter and resistor How do the values of current through the nichrome wire and potential difference across the two ends of it may change? This verifies Ohm’s law. A simple circuit to verify Ohm's law Take four or five dry cells, a thin wire (AB), a voltmeter, an ammeter, a plug key and some thick connecting wires. (c) rheostat (b) Secondary cells can be recharged using a charger. (c) incorrect readings If charge $q_0$ is given a small displacement $y ( y << a)$ along the y-axis, the net force acting on the particle is proportional to, Diameter of a plano-convex lens is 6 cm and thickness at the, A charge Q is uniformly distributed over a long rod AB of length L as shown in the figure. 2) Ammeter is always connected in series in the circuit while voltmeter is parallel to the conductor. Range of voltmeter = VR…………………… (c) resistor Identify the circuit in which the electrical components have been properly connected. The potential difference V across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains same. The straight line of the graph indicates that current I is directly proportional to voltage V. Question 8: KCL AND KVL DEEE-EMS LAB SAI SPURTHI INSTITUE TECHNOLOGY- B.GANGARAM VERIFICATION OF KIRCHOFF CURRENT AND VOLTAGE LAWS AIM: To verify Kirchhoff’s current law and voltage law. Аnswer: The voltmeter is always connected in parallel in a circuit. (d) all of these, Questions based on Observational Skills (a) The voltmeter has been correctly connected in the circuit. Ohm's Law 1. What is the unit of potential difference and how do we measure potential difference? (a) Voltmeter Question 17: (a) 0.020 V The SI unit of resistance of a wire is Question 4: The piston is slightly displaced from the equilibrium position and released. For the experiment “to find the equivalent resistance of the two given resistors connected in parallel” the following circuit was drawn by a student. The current flowing through a conductor and the potential difference across its two ends are as per reading of the ammeter and the voltmeter shown below. To calculate the least count of voltmeter. Ohm’s Law can be easily verified by the following experiment: Appartus Required: Resistor; Ammeter; Voltmeter; Battery; Plug Key; Rheostat; Circuit Diagram: Procedure: Initially, the key K is closed and the rheostat is adjusted to get the minimum reading in Ammeter A and voltmeter. Color coding technique is used to represent the values of resistors in the form of colored bands. (b) ammeter The instrument used to measure the potential difference is In the above circuit diagram, the components connected in parallel are: (b) power It is measured by an instrument called the voltmeter. (a) 0.02 A The amount of heat, extracted from the source in a single cycle is. Current should be passed through the circuit for a short time while taking observations; otherwise current would cause unnecessary heating in the circuit. Also plot a graph between V and I. (b) Ammeter is in series and voltmeter is in parallel. If the resistor of a known resistance value is replaced with a nichrome wire of 10 cm length (say). Thus, this law of Ohm can be expressed with the equation or formula, V = IR Thus, the derivation of Ohm’s law is done. Name of the apparatus Range Type Quantity 1 Ammeter 0-100mA 1 No. In a voltmeter there are 20 divisions between the 0 mark and 0.5 V mark. The graph of V-I is a straight line. The work done in moving a unit charge from one point to the other is called potential difference. - [Presenter] Let's explore how we can practically verify whether any material obeys Ohm's law. The rate of flow of charge in a conductor is called electric current. (a) Primary cell like dry cell, Lechlanche cell is used in torch, transistors etc. (b) 1.5 Ω (a) damage of instrument The teacher pointed out the possibility of the following faults: Ohm expressedhis discovery in the form of a simple equation, describing how voltage, current,and resistance related to each other: V=IRHypothesisThe experiment setup consists of a simple circuit with a variable resistance andsimple power source, which are 3 batteries (1.5 Volt each). The resistance of nichrome is more as compared to manganin. Question 36: The plot correctly showing the dependence of the current 1 on the potential difference V across a resistor R is. Questions based on Reporting and Interpretation Skills This shows that V∝I. (d) coulomb, Question 6: In the given circuit diagram, the components connected in series are: (d) 1 V and 1 A. The fringes obtained on the screen will be, A beam of unpolarized light of intensity $I_0$ is passed through a polaroid $A$ and then through another polaroid $B$ which is oriented so that its principal plane makes an angle of 45$^{\circ}$ relative to that of $A$. (d) galvanometer, Question 3: (d) Through series, the current flows the same. While performing Ohm’s law experiment a student observed that the pointer of the voltmeter coincides with 15th division. Question 22: Ohm’s law is a simple empirical law that relates the conductivity in a material to the current density flowing through it. Question 36: (a) increases with temperature (a) Reading = Least count x Division of reading. (d) none of these. How will you use such ammeter (or voltmeter) in the circuit? (c) 0.050 V Calculate resistance of a given resistor by formula. 4 Resistors 50Ω, 100Ω, 0.5Watt … Question 5: What is the decrease of voltage across the bulb, when a $240\, W$ heater is switched on in parallel to the bulb? Theory. An ammeter has 20 divisions between mark 0 and mark 2 on its scale. The ends of the wire may get corroded or some impurities may be deposited on it hence to remove the same and get correct readings the ends of the wire should be cleaned. A. Аnswer: (d) some reading in the voltmeter but no reading in ammeter. Suggest the material needed to him to do the related activity. The resistance of a resistor is ratio of potential difference V and current I. • Test the validity of Ohm’s law. Question 9: Аnswer: (a) wrong connections What does the straight line of a graph indicate? The number of charges flowing through a given wire in unit time is called electric current. Make the connections as per circuit diagram. Question 40: 4, 5 or 6 bands are designed over the bodies of resistors. A sonometer wire of length 1.5 m is made of steel. (c) Ammeter, Voltmeter and Rheostat (b) ammeter and voltmeter (a) same reading in both the ammeter and the voltmeter (a) no reading in either the ammeter or the voltmeter. 3 Digital multimeter. We need to identify the positive and negative terminal of the device by connecting it to the battery. Аnswer: Question 9: It is important to know this because you need to make sure you are draining a safe amount of energy from your battery at all times. Question 1: The value of resistance of the resistor in Ohm is Аnswer: On replacing nichrome wire with manganin the current will increase and the potential difference will increase. Least count of voltmeter = =  ………………. When 1 joule of work is done to move a charge of 1 coulomb from one point to the other, then potential difference D. the rheostat and the key were not correctly connected in the circuit This law states that voltage is equal to the product of the total current and the total resistance. What is the value of charge in 1 electron? What will you infer if the deflection takes place in opposite direction? (b) B and C Question 3: (c) rheostat and ammeter Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. The intensity of the emergent light is, An ideal gas enclosed in a vertical cylindrical container supports a freely moving piston of mass $M$. Thus, … (c) is constant with rise in temperature Аnswer: The resistance of an alloy (a) I is directly proportional to V. Hence, straight line graph. (b) resistor and voltmeter It produces 1.5 volts of p.d. 3) The electrical current should not flow the circuit for long time, Otherwise its temperature will increase and the result will be affected. (d) a finite reading in both the ammeter and the voltmeter. The value of R is found to be same and constant in all three readings. It is measured by a device called ammeter which is always connected in series in a circuit. By using the slider of rheostat take three different readings of current 1 and voltmeter V. Record your observations in the observation table. Ohms Law Pie Chart. (c) (d) in set-up (A) and (a) in set-up (B). OHMS LAW . Question 19: In (B) as, the initial point at rheostat is in circuit therefore, minimum resistance is in circuit. (d) ammeter and voltmeter. is of 1 volt. The current flowing through a resistor connected in an electrical circuit and the potential difference developed across its ends are shown in the given diagram. Question 43: Question 24: Once the circuit is connected, insert the key and check the rheostat, adjust its slider and see whether the ammeter and voltmeter readings are shown. Experimental Verification of Ohm’s Law. Question 5: Question 6: Ohms Law. (d) 1 A in circuit I and 1 A in circuit II. In a circuit ammeter is always connected in series and voltmeter is connected in parallel across the points between which potential difference is to be measured. (d) negative error. (d) 0.01. (d) becomes four times, Question 13: Positive terminal of the battery is connected to the positive terminal of the ammeter. The area of cross-section of the resistor. (c) 3 Ω For the two students, the value of the emf used by student (A) and the resistance due to the rheostat What will happen to current passing through a conductor if potential difference across it is doubled and the resistance is halved? For effective use should be used intermittently. Question 4: (c) ohm Question 2: Use Ohms law to relate resistance, current and voltage. Semiconductor Electronics: Materials Devices and Simple Circuits, The shown p- V diagram represents the thermodynamic cycle of an engine, operating with an ideal monoatomic gas. The ammeter should be connected in series with the resister such that the current enters at the positive terminal and leaves at the negative terminal of the ammeter. The diagram besideshows the single circuit that we will use for thisexperiment:We could choose a Voltage … The process is: A screw gauge has least count of 0.01 mm and there are 50 divisions in its circular scale. The approximate value of the resistor is: Question 21: (b) Ammeter B. the voltmeter was not correctly connected in the circuit The resistance of the conductor would be: Question 23: JEE Main 2013: Correct set up to verify Ohm’s law is: (A) Image A (B) Image B (C) Image C (D) Image D. Check Answer and Solution for above Physics q unit of current is ampere. (b) Voltmeter, Ammeter and Resistance Using Circuit Simulators for Validating Ohm’s Law. Question 35: An ammeter has a range of (0-3) ampere and there are 30 divisions on its scale. single resistor to verify Ohm's Law using resistors in dc circuits 2. Number of divisions in voltmeter = VN Procedure : 1. To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. A particle of mass m and charge $q_0=\frac{q}{2}$ is placed at the origin. (a) 0 V in both the circuits Аnswer: (c) some reading in the ammeter but no reading in the voltmeter. In an electric circuit Battery, Plug key, Ammeter, Iron nail are connected in Series combination. (c) ammeter and rheostat (d) 0.250 V. Question 10: The supply voltage in a room is $120\, V$. 2.2 APPARATUS REQUIRED: S. No Apparatus Name Range Type Quantity 1 RPS 2 Ammeter 3 Voltmeter 4 Resistor 5 Rheostat 6 Bread Board 7 Connecting Wires 2.3 CIRCUIT DIAGRAM: Fig – 2.1 Circuit Diagram 2.4 PROCEDURE: 1. Question 10: (c) 0.2 A Ohms law can be used to identify the relationship between voltage, current, and resistance in any DC electrical circuit discovered by a German physicist named, Georg Ohm. (b) 0.01 A (d) joule, Question 4: (b) In (A) as only cell is in circuit, therefore, voltmeter reads minimum emf. Question 29: For which one of the following, Bohr model is not valid? Science Lab Manual Class 10 Experiment – 1, Aim Jyothi Lakshmi wants to verify Ohm’s law experimentally. Keep the devices as shown in the circuit diagram. (d) 0.1 A. Connect them with the connecting wires and keep the key open. (c) 1 A in both the cases Range of ammeter = AR……………………. (d) The resistors R1 and R2 have been correctly connected in parallel. (d) Least count is range divided by number of divisions. A battery, an insulated copper wire (cut into 10 pieces), a key, an ammeter, a voltmeter, a rheostat, a resistor and a piece of sand paper. Thus, ohm’s law is verified by this experiment. Volt meter is connected at the ends of the iron nail in parallel combination. Such cells are also called accumulators or storage cells. A straight line graph obtained between V and I verifies the Ohm’s law. • Construct series and parallel circuits. (d) 2 Ω. (c) The reading is shown on switched off circuit. Аnswer: Note down the potential difference (V) across the conductor PQ of resistance R shown by the voltmeter and the corresponding current (I) shown by the ammeter. (d) rheostat. Define potential difference. On x axis take V and on y axis take I. 2. The resistance of a wire depends on Ohm’s Law is named after George Simon Ohm a German physicist. Ohm’s Law and Kirchhoff’s Laws place constraints on voltages and current within a circuit, thus providing important information about these variables. If the deflection takes place in opposite direction than the connections need to be checked and the terminals need to be interchanged. The entire system is thermally insulated. A voltmeter should have: (d) resistor and voltmeter. In this experiment it is advised to take out the key from the plug when the observations are not being taken. (a) Voltmeter is connected in parallel while ammeter is connected in series. 1 No. Connections should be tight otherwise some external resistance may introduce in the circuit. NCERT Solutions for Class 8 Science Chapter 18 Pollution of Air and Water, NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System, NCERT Solutions for Class 8 Science Chapter 16 Light, NCERT Solutions for Class 8 Science Chapter 15 Some Natural Phenomena, NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current, NCERT Solutions for Class 8 Science Chapter 13 Sound, NCERT Solutions for Class 8 Science Chapter 12 Friction, NCERT Solutions for Class 8 Science Chapter 11 Force and Pressure, NCERT Solutions for Class 8 Science Chapter 10 Reaching the Age of Adolescence, NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animals, NCERT Solutions for Class 8 Science Chapter 8 Cell Structure and Functions, NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals, NCERT Solutions for Class 8 Science Chapter 6 Combustion and Flame. What is the least count? (b) Least count is range divided by number of divisions. (b) low resistance (b) no reading in the voltmeter but a finite reading in the ammeter. Аnswer: (c) Straight line is obtained as V and I are directly proportional to each other. The stop cock is suddenly opened. The current flowing through a resistor connected in an electric circuit and potential difference developed across its ends are shown in the diagram. (a) volt In a circuit ammeter is always connected in series and voltmeter is always connected in parallel. The least count of the ammeter is (b) decreases with temperature What is the gravitational force on it, at a height equal to half the radius of the earth? To verify Ohm's law, a student connects the voltmeter across the battery as, shown in the figure. According to Ohm’s law, the relationship between V, I and R is, Question 8: (c) moderate resistance It is the property of a conductor to resist the flow of charges through it. What is the unit of current and how do we measure current flowing through a wire? A body weighs 72 N on the surface of the earth. Why? Do not proceed with your experiments until your TA has checked the circuit. According to ohm’s law, the resistance R is the ratio of the voltage U across a conductor and the current I flowing through it: What is Ohm’s law? (b) ampere volt. Define 1 volt. Аnswer: NCERT Solutions for Class 6 Social Science History Chapter 1 What, Where, How and When? It should be non-zero number. When the piston is in equilibrium, the volume of the gas is $V_0$ and its pressure is $p_0$. To make electric heater the wire used should be offering high resistance. In Ohm’s circuit which of the following does not have © and © terminals? While you don’t have to COMPLETELY know and understand ohms law ,because there are formulas on our web site that will help you with the math, you do have to understand that ohms law will guide you to select the correct value components needed to safely operate your lads; specifically the current limiting resistors needed. If the potential difference across the ends of a conductor is 1 volt and the current flowing through it is 1 ampere, then resistance of the conductor is 1 ohm. (c) 7.5 V Question 11: (a) Potential difference is measured by voltmeter. What will you infer from such an observation? A student arranged an electric circuit as shown below: .’. (b) Resistor and voltmeter are the two components connected in parallel. The unnecessary current flows through the circuit causes the heating effect and changes the resistance. The given graph, is plotted for V-I to verify Ohm’s law. Here you can perform simple experiments remotely from home or elsewhere using resistors and instruments located in an instructional laboratory at Blekinge Institute of Technology in Sweden. Calculate the least count of voltmeter and ammeter correctly. (c) Least count is range divided by number of divisions. Question 5: IMPORTANT: Special concerns for Ohm’s law experiment 1. To verify Ohm’s law the given circuit diagram was drawn by a student. Two coherent point sources $S_1$ and $S_2$ are separated by a small distance $d$ as shown. Simple to use Ohm's Law Calculator. Question 33: (c) The ON switch will interfere in correct readings as some current will keep flowing. A contains an ideal gas at standard temperature and pressure. Question 20: NAME OF THE APPARATUS; S.No. Question 37: Question 28: The correct arrangement is: Question 41: Аnswer: The nature of resistor (a conductor having some resistance.). (b) It is the correct statement for the circuit. (b) length of the wire $ What is the fundamental frequency of steel if density and elasticity of steel are $7.7 \times 10^3 \, kg/m^3 \, and \, 2.2 \times 10^{11} N/m^2 $ respectively? Correct answer: 4. (b) Circuit B can help in verification of ohm’s law. (d) (a) in set-up (A) and (d) in set-up (B). In an electric circuit containing resistance, ammeter, key and battery, where will you connect voltmeter to verify Ohm’s law? (potential difference). The current flowing through a resistor connected in a circuit and the potential difference developed across its ends are as shown in the diagram. (b) (a) in both the set-ups. The unit of electric current is (b) 0 A in both the cases B is completely evacuated. (a) A and B While 4 band resistors are most commonly available we’ll use them in next problems. Ohm's law states that under constant temperature, the current passing through conductor is directly proportional to potential difference applied across it. (b) The ammeter has been correctly connected in the circuit. 3. Аnswer: Connect the various components as. (a) volt (c) becomes halved Question 27: Аnswer: • Construct a circuit using resistors, wires and a breadboard from a circuit diagram. In 1 coulomb 6.25 x 1018 electrons are present. On increasing the length of the resistor its resistance increases. (b) zero error (c) C and D In an experiment to study dependence of current on the potential difference across a given resistor, four students P, Q, R and S kept the plug key in the circuit closed for time t{ and then open for time t2 as given in the table below: The best choice of open and closed time is that of student (c) 2 V and 1 A Suppose in this experiment you see that the deflection on ammeter (or voltmeter) scale goes beyond the full scale. The SI unit of potential difference is volt (V). Just enter 2 known values and the calculator will solve for the others. Аnswer: Which two components are connected in the series? A. (c) cross-sectional area of wire (c) ohm OR What is meant by least count of an instrument? Ohm's law Introduction. To verify Ohm’s Law by calculating voltage, current and resistance based on different views of Ohm’s law, as well as measuring those values to compare the theoretical results with the actual results. Question 2: (1) Here, Here R is a constant for the given element and is called its resistance. What precautions should be taken to do Ohm’s law experiment ? 2. Aim of experiment The main purpose of this laboratory experiment is: to learn the proper use of electrical meters to measure the resistance of resistor by different methods to examine the current-voltage relation for the simplest circuit element i.e. When the flow of current was studied it was assumed that the positive electricity is flowing from higher potential to lower potential. If in the ammeter, there are 10 divisions from 0 to 0.1 A then each division indicates 0.01 A. (c) Current (I) =V/R= 1 A and potential difference (V) = RI = 2V. Why is it advised to clean the ends of connecting wires before connecting them? In the circuit given below the voltmeter and ammeter readings are respectively What are the factors that affect resistance? (d) none of these, Question 2: Connections should be made as per the circuit. Now move the knob of rheostat so that the current in the circuit increases. What is coulomb? They kept the contact J in four different positions, marked (a), (b), (c) and (d) in the two figures. Аnswer: Question 9: (a) battery and ammeter (b) 27 (c) ammeter and rheostat (a) battery and Voltmeter (a) Ammeter, Voltmeter and Resistance What is resistance? Question 6: (c) joule (b) length of wire C. the resistors IT and R2 were not correctly connected in parallel. Аnswer: The resistance of a wire depends on: Principles 2.1. Give its SI unit. The graph is a straight line. (d) Resistance depends on all the given factors. Question 38: Аnswer: Voltmeter will be connected parallel to the resistance. If the length of a given resistor is increased, what will happen to the overall resistance? Question 26: The unit of current is ampere. If your circuit is not properly connected, it is possible to damage the electronic equipment used in this lab. 5. Number of divisions in ammeter = AN………………………….. Ohms law is an equation that will work out for you the amount of energy current you are drawing from your battery whilst you vape a mechanical mods. The best graph plotted by a student for Ohm’s experiment is: Question 39: This helps in taking accurate readings. (b) In series is ammeter, in parallel is voltmeter and Z is symbol of resistance. (c) no reading in the ammeter but a finite reading in the voltmeter. .’. (b) 0.025 V To help us understand the the relationship between the various values a little further, we can take all of the Ohm’s Law equations from above for finding Voltage, Current, Resistance and of course Power and condense them into a simple Ohms Law pie chart for use in AC and DC circuits and calculations as shown. In circuit II, the current flows and hence 2V. B. (d) Resistor, Question 18: The graph of V and I is a straight line. To verify Ohm’s law for a given resistive network. It is measured by the device called ammeter. Аnswer: The piston and the cylinder have equal cross-sectional area $A$. Question 31: The two faults pointed out correctly by the teacher, are (d) In circuit I, the key is open, so 0V. (d) As per Ohm’s law of formula calculation. How the values will change if the replaced wire is of manganin in place of nichrome? Question 3: In the experiment if the deflection on ammeter or voltmeter scale goes beyond the full scale than the device needs to be replaced with the one which can measure higher current and voltage. A student wanted to make a battery of 6 V of cells with e.m.f 1.5 V each. The plug key allows you to switch off the current when not required. 2 GΩ; Ohm’s law Quiz MCQs with Resistor Color Coding Technique. Questions based on Procedural and Manipulative Skills Heating may change the resistance of resisters. (c) resistance 4. The least value that an instrument can measure is called its least count. Find the value of the resistance of the resistor is. 249 kPa and temperature $27^\circ\,C$. Question 2: Which of the following set-up is correct for the verification of Ohm’s law. Question 8: Question 34: (a) remains unchanged The least count of the voltmeter is (b) 1 V and 2 A Voltmeter should always be connected in parallel to resistor. (d) Voltmeter, Ammeter and Rheostat. The unit of charge is 1 electron = 1.6 x 10-19C. Suppose the ammeter (or voltmeter) you are using in this experiment do not have positive (+) and negative (-) terminal markings. Close the sky, so that current begins to flow in the circuit. Ohm performed repeated experiments on a resistor, applied different voltages, measured current and found relationship between these quantities. Define 1 ohm. Question 37: The graph of V-I is a straight line.