Class 10th Science Lab Manual CBSE Solution
Lab Experiment 5aLab Experiment 5bViva Questions- What is zero error?
- What is least count?
- Suppose the ammeter you are using in this experiment does not have positive and negative…
- Suppose the deflection go beyond the full scale. What will you infer from such…
- Why it is advised to clean the ends of connecting wires before connecting them?…
- While taking the reading the student observe that pointer on voltmeter is 15th division…
- In a series combination, what happens to voltage and current?
- What is the equivalent resistance for a series combination parallel combination?…
- In parallel combination, is the current same or voltage same in the circuit?…
- Why are the standard resistances made up of manganin wire?
- What should be characteristics of standard resistance?
- Why connecting wires are made of copper?
- How many times will be the equivalent resistance of two identical resistors be increased…
- Can you distinguish between resistor and resistance?
- In what way household appliances should be connected?
- Draw a diagram which shows the direction of current the current carriers.…
- Why is ammeter always connected in series in a circuit?
- Why is voltmeter always connected in parallel?
- Which device has high resistance voltmeter or ammeter?
- Why closed path is required for flow of current?
- What happens to the resistance of a conductor if the area of cross section is increased?…
- Why are copper and aluminium wires used for electrical transmission?…
- What helps to maintain the potential difference across a conductor?…
- Write one advantage of connecting devices in parallel and not in series.…
- Give one difference between open circuit closed circuit?
- What is zero error?
- What is least count?
- Suppose the ammeter you are using in this experiment does not have positive and negative…
- Suppose the deflection go beyond the full scale. What will you infer from such…
- Why it is advised to clean the ends of connecting wires before connecting them?…
- While taking the reading the student observe that pointer on voltmeter is 15th division…
- In a series combination, what happens to voltage and current?
- What is the equivalent resistance for a series combination parallel combination?…
- In parallel combination, is the current same or voltage same in the circuit?…
- Why are the standard resistances made up of manganin wire?
- What should be characteristics of standard resistance?
- Why connecting wires are made of copper?
- How many times will be the equivalent resistance of two identical resistors be increased…
- Can you distinguish between resistor and resistance?
- In what way household appliances should be connected?
- Draw a diagram which shows the direction of current the current carriers.…
- Why is ammeter always connected in series in a circuit?
- Why is voltmeter always connected in parallel?
- Which device has high resistance voltmeter or ammeter?
- Why closed path is required for flow of current?
- What happens to the resistance of a conductor if the area of cross section is increased?…
- Why are copper and aluminium wires used for electrical transmission?…
- What helps to maintain the potential difference across a conductor?…
- Write one advantage of connecting devices in parallel and not in series.…
- Give one difference between open circuit closed circuit?
Lab Experiment 5a
Question 1.AIM
To determine of the equivalent resistance of two resistors when connected in series.
Answer:MATERIALS REQUIRED
Two standard resistance coils, ammeter, voltmeter, one - way plug key, low resistance rheostat, connecting wires, cell or battery eliminator.
THEORY
When two or more resistors are connected end to end, then they provide only one path to the flow of current i.e., the same current flow through each resistor. Then, they are in series combination.
V = V1 + V2
let v be the applied potential difference by a dc source across the combination of unknown resistors R1 and R2.
According to ohms law, for each resistor,
V1 = IR1, V2 = IR2
Then the equivalent resistance of the series combination of two resistors is given by
Rs = R1 + R2
Circuit Diagram
Apparatus Arrangement:
PROCEDURE
1. Join the circuit as shown in the circuit diagram or apparatus arrangement with one of the unknown resistors.
2. Find the values of two given unknown resistors R1 and R2 one by one.
3. Tabulate at least three readings of ammeter and voltmeter for the given unknown resistor.
4. By using Ohm’s law, find the value of each resistance.
5. Connect the given resistors in series combination between the terminals of voltmeter as shown in the figure above
6. Plug in the one - way plug key and note the readings of ammeter and voltmeter in the observation table.
7. Repeat the step 6 three times by changing the position of the sliding contact of the rheostat
8. Write the readings and find the ratio of V and I. It will give the equivalent resistance of the combination.
OBSERVATION TABLE
OBSERVATIONS
1. Least count of ammeter:
The image of the ammeter is attached here:
The range of the ammeter =500 - 0 mA = 500 mA = 0.5 A
The number of divisions in between two consecutive values= 10
Therefore, the least count = 
= 0.01 A
2. Zero error of ammeter:
The needle of the ammeter points towards zero of the main scale of the ammeter, therefore no zero error .
3. Least count of voltmeter:
The range of voltmeter = 2 - 0 V= 2 V.
The number of division in small scale between two division on the main scale
= 10
Therefore, the least count
4. Zero error of voltmeter = 0 V.
CALCULATIONS
1. Mean value of R1 = 2.06 Ω
2. Mean value of R2 = 4.06 Ω
Equivalent value of series combination:
(a) by calculation, = 2 Ω + 4 Ω = 6 Ω
(b) by experiment, = 5.99 Ω
Difference in both value = Rexp – Rcalculated= 0.01 Ω
RESULT
1. The calculated and the experimental value of equivalent resistance are similar. Hence Rs = R1 + R2 is verified.
2. The equivalent resistance, Rs = 5.99 Ω
PERCENTAGE ERROR
Percentage error = 
= 0.16667 %
PRECAUTIONS
1. Remove the oxide layer from the ends of connecting wires by rubbing it with sandpaper.
2. All connections should be kept tight and properly done as per the circuit diagram.
3. Take out the plug from the plug key in between the two observations to avoid heating.
4. A low resistance rheostat should be used in the circuit to obtain a large variation in current.
5 A thick copper connecting wire should be used in the circuit.
AIM
To determine of the equivalent resistance of two resistors when connected in series.
Answer:
MATERIALS REQUIRED
Two standard resistance coils, ammeter, voltmeter, one - way plug key, low resistance rheostat, connecting wires, cell or battery eliminator.
THEORY
When two or more resistors are connected end to end, then they provide only one path to the flow of current i.e., the same current flow through each resistor. Then, they are in series combination.
V = V1 + V2
let v be the applied potential difference by a dc source across the combination of unknown resistors R1 and R2.
According to ohms law, for each resistor,
V1 = IR1, V2 = IR2
Then the equivalent resistance of the series combination of two resistors is given by
Rs = R1 + R2
Circuit Diagram
Apparatus Arrangement:
PROCEDURE
1. Join the circuit as shown in the circuit diagram or apparatus arrangement with one of the unknown resistors.
2. Find the values of two given unknown resistors R1 and R2 one by one.
3. Tabulate at least three readings of ammeter and voltmeter for the given unknown resistor.
4. By using Ohm’s law, find the value of each resistance.
5. Connect the given resistors in series combination between the terminals of voltmeter as shown in the figure above
6. Plug in the one - way plug key and note the readings of ammeter and voltmeter in the observation table.
7. Repeat the step 6 three times by changing the position of the sliding contact of the rheostat
8. Write the readings and find the ratio of V and I. It will give the equivalent resistance of the combination.
OBSERVATION TABLE
OBSERVATIONS
1. Least count of ammeter:
The image of the ammeter is attached here:
The range of the ammeter =500 - 0 mA = 500 mA = 0.5 A
The number of divisions in between two consecutive values= 10
Therefore, the least count =
= 0.01 A
2. Zero error of ammeter:
The needle of the ammeter points towards zero of the main scale of the ammeter, therefore no zero error .
3. Least count of voltmeter:
The range of voltmeter = 2 - 0 V= 2 V.
The number of division in small scale between two division on the main scale
= 10
Therefore, the least count
4. Zero error of voltmeter = 0 V.
CALCULATIONS
1. Mean value of R1 = 2.06 Ω
2. Mean value of R2 = 4.06 Ω
Equivalent value of series combination:
(a) by calculation, = 2 Ω + 4 Ω = 6 Ω
(b) by experiment, = 5.99 Ω
Difference in both value = Rexp – Rcalculated= 0.01 Ω
RESULT
1. The calculated and the experimental value of equivalent resistance are similar. Hence Rs = R1 + R2 is verified.
2. The equivalent resistance, Rs = 5.99 Ω
PERCENTAGE ERROR
Percentage error = = 0.16667 %
PRECAUTIONS
1. Remove the oxide layer from the ends of connecting wires by rubbing it with sandpaper.
2. All connections should be kept tight and properly done as per the circuit diagram.
3. Take out the plug from the plug key in between the two observations to avoid heating.
4. A low resistance rheostat should be used in the circuit to obtain a large variation in current.
5 A thick copper connecting wire should be used in the circuit.
Lab Experiment 5b
Question 1.AIM
To determine the equivalent resistance of two resistors when connected in parallel.
Answer:MATERIALS REQUIRED
Two standard resistance coils, ammeter, voltmeter, one-way plug key, a low resistance rheostat, connecting wires, battery or battery eliminator.
THEORY
An arrangement in which resistors are connected between two common ends of the circuit in such a way that the potential difference across each resistance is equal to the applied voltage, then such an arrangement is called the parallel combination
As shown in the figure, two resistances R1 and R2 are connected between two points A and B in the parallel combination.
Let the potential applied by the dc source to this combination be V. let I1 and I2 be the current measured by ammeters, connected in series with the resistor R1 and R2 respectively, then
I = I1+I2
According to ohms law, I1 = V/R1 and I2 = V/R2
If Rp, is the equivalent resistance of the given parallel combination having the same potential difference a the applied potential, then
or 
Circuit Diagram
Apparatus Arrangement Diagram:
Connect all the resistors in parallel combination between the two terminals of the voltmeter as shown in the figure given below.
PROCEDURE
1. Connect the circuit as shown in the circuit diagram with one of the unknown resistors.
2. By using Ohm’s law, find the value of each resistance, Let it be R1 or R2.
3. Connect the given resistors in parallel combination between the two terminals of the voltmeter as shown in the circuit diagram above.
4. Plug in the key and take the readings of ammeter and voltmeter.
5. Repeat the step 5 for three times by changing the position of the sliding contact of the rheostat.
6. Record the readings in the observation table and find the ratio of V and I. It will give the equivalent resistance of the combination.
OBSERVATION TABLE
Observation:
The image of the ammeter is attached here:
The range of the ammeter = 500 - 0 mA = 500 mA = 0.5 A
The number of divisions in between two consecutive values = 10
Therefore, the least count = 
= 0.01 A
2. Zero error of ammeter:
The needle of the ammeter points towards zero of the main scale of the ammeter.
3. Least count of voltmeter:
The range of voltmeter = 2 - 0 V = 2 V.
The number of division in small scale between two division on the main scale
= 10
Therefore, the least count
4. Zero error of voltmeter = 0 V.
CALCULATIONS
1. Mean value of R1 = 2.083 Ω
2. Mean value of R2 = 1.973 Ω
Equivalent value of parallel combination:
(a) by calculation, R = 1 Ω
(b) by experiment, R = 1.08 Ω
RESULT
1. The equivalent resistance of parallel combination = 1.08 Ω.
2. There is a direct agreement between the calculated value and the experimental value.
Hence, 
is verified.
PERCENTAGE ERROR
Percentage error 
Percentage error = 8%
Precautions:
1. All the connection should be tight and properly done as per circuit diagram.
2. Take out the plug from the plug key in between the two observations.
3. A low resistance rheostat should be used in the circuit to obtain large variation in current.
4. A thick copper connecting wires should be used in the circuit.
5. The positive terminal of the ammeter and voltmeter must be connected with the positive terminal of the battery or battery eliminator.
AIM
To determine the equivalent resistance of two resistors when connected in parallel.
Answer:
MATERIALS REQUIRED
Two standard resistance coils, ammeter, voltmeter, one-way plug key, a low resistance rheostat, connecting wires, battery or battery eliminator.
THEORY
An arrangement in which resistors are connected between two common ends of the circuit in such a way that the potential difference across each resistance is equal to the applied voltage, then such an arrangement is called the parallel combination
As shown in the figure, two resistances R1 and R2 are connected between two points A and B in the parallel combination.
Let the potential applied by the dc source to this combination be V. let I1 and I2 be the current measured by ammeters, connected in series with the resistor R1 and R2 respectively, then
I = I1+I2
According to ohms law, I1 = V/R1 and I2 = V/R2
If Rp, is the equivalent resistance of the given parallel combination having the same potential difference a the applied potential, then
or
Circuit Diagram
Apparatus Arrangement Diagram:
Connect all the resistors in parallel combination between the two terminals of the voltmeter as shown in the figure given below.
PROCEDURE
1. Connect the circuit as shown in the circuit diagram with one of the unknown resistors.
2. By using Ohm’s law, find the value of each resistance, Let it be R1 or R2.
3. Connect the given resistors in parallel combination between the two terminals of the voltmeter as shown in the circuit diagram above.
4. Plug in the key and take the readings of ammeter and voltmeter.
5. Repeat the step 5 for three times by changing the position of the sliding contact of the rheostat.
6. Record the readings in the observation table and find the ratio of V and I. It will give the equivalent resistance of the combination.
OBSERVATION TABLE
Observation:
The image of the ammeter is attached here:
The range of the ammeter = 500 - 0 mA = 500 mA = 0.5 A
The number of divisions in between two consecutive values = 10
Therefore, the least count =
= 0.01 A
2. Zero error of ammeter:
The needle of the ammeter points towards zero of the main scale of the ammeter.
3. Least count of voltmeter:
The range of voltmeter = 2 - 0 V = 2 V.
The number of division in small scale between two division on the main scale
= 10
Therefore, the least count
4. Zero error of voltmeter = 0 V.
CALCULATIONS
1. Mean value of R1 = 2.083 Ω
2. Mean value of R2 = 1.973 Ω
Equivalent value of parallel combination:
(a) by calculation, R = 1 Ω
(b) by experiment, R = 1.08 Ω
RESULT
1. The equivalent resistance of parallel combination = 1.08 Ω.
2. There is a direct agreement between the calculated value and the experimental value.
Hence, is verified.
PERCENTAGE ERROR
Percentage error
Percentage error = 8%
Precautions:
1. All the connection should be tight and properly done as per circuit diagram.
2. Take out the plug from the plug key in between the two observations.
3. A low resistance rheostat should be used in the circuit to obtain large variation in current.
4. A thick copper connecting wires should be used in the circuit.
5. The positive terminal of the ammeter and voltmeter must be connected with the positive terminal of the battery or battery eliminator.
Viva Questions
Question 1.What is zero error?
Answer:If the pointer of the meter does not coincide with zero of the scale, this type of error in reading of the scale is called a Zero error.
Question 2.What is least count?
Answer:The smallest value that can be measured accurately by an instrument is called its least count.
Question 3.Suppose the ammeter you are using in this experiment does not have positive and negative markings , How will you use such ammeter?
Answer:We will connect the ammeter or Voltmeter arbitrary in the circuit and observe the deflection of the pointer. If the deflection occurs in the opposite direction then by interchanging the terminal connection, we can use these devices.
Question 4.Suppose the deflection go beyond the full scale. What will you infer from such observation?
Answer:If the deflection on ammeter goes beyond the full scale , we infer that:
1. The higher range ammeter has to be used to measure higher current.
2. The applied voltage is very high thus will require a high range voltmeter to measure applied voltage
Question 5.Why it is advised to clean the ends of connecting wires before connecting them?
Answer:It is advised to clean the ends of connecting wires to remove the insulating layer if any from to ends of the wire. Also, to remove any dust from the ends of the wire to ensure better flow of electrons in the junction.
Question 6.While taking the reading the student observe that pointer on voltmeter is 15th division when voltmeter least count is 0.05V. Find the observed reading of voltmeter?
Answer:Observed reading = Least count × Number of division
= 0.05 × 15
= 0.75 V
Question 7.In a series combination, what happens to voltage and current?
Answer:In series combination:
1. Current flowing across a different resistor connected in series are same
2. Voltage in a series is the sum of the voltage across the different resistor.
Question 8.What is the equivalent resistance for a series combination & parallel combination?
Answer:The equivalent resistance Req=R1+R2+…….+Rn.
The equivalent resistance in a parallel connection is given as:
Question 9.In parallel combination, is the current same or voltage same in the circuit?
Answer:In parallel combination:
1. The voltage across the resistor remains the same.
2. The current across the combination is the sum of the current across the different resistor.
Question 10.Why are the standard resistances made up of manganin wire?
Answer:The standard resistance coils are made up of manganin wire. The reasons are:
i. The variation of resistance with a rise in temperature is very less as compared to other metal.
ii. The resistivity of the material is very high & any resistance value can be made from it. Therefore, it is used as standard resistance.
Question 11.What should be characteristics of standard resistance?
Answer:1. The value of resistance should not change with time.
2. The value of resistance should almost remain the same with a change in temperature.
3. It should be convenient sizes.
Question 12.Why connecting wires are made of copper?
Answer:The connecting wires are made of copper because copper has low resistivity and it conducts the current without offering much resistance.
Question 13.How many times will be the equivalent resistance of two identical resistors be increased if the parallel arrangement is changed to a series arrangement?
Answer:The effective resistance in parallel combination is 
That of series combination is Rs = 2R. Thus, we get Rs = 4Rp, i.e., equivalent resistance increases four times.
Question 14.Can you distinguish between resistor and resistance?
Answer:The resistor is a device which offers resistance, whereas resistance is the property of the resistor.
Question 15.In what way household appliances should be connected?
Answer:The household appliances should be connected in parallel in order to get equal voltage for each appliance and ensure that if one is a switch “on” or ”off,” others working are not affected.
Question 16.Draw a diagram which shows the direction of current & the current carriers.
Answer:The direction of current is from the positive terminal of the battery, it goes on through the components & then enters through negative terminal.
The current carriers are electrons and the motion of electrons is opposite from the electric current.
Question 17.Why is ammeter always connected in series in a circuit?
Answer:Ammeter is always connected in series with circuit as it should offer low resistance to the components added in the series. In this ways, the current can be measured accurately in low resistance.
Question 18.Why is voltmeter always connected in parallel?
Answer:Voltmeter should be connected in parallel because in parallel connection, the potential difference is same.
Question 19.Which device has high resistance voltmeter or ammeter?
Answer:Voltmeter has very high resistance and ammeter has negligible resistance. This is because when voltmeter is connected in parallel across any two points, it will draw very less current (due to high resistance), hence it can measure the voltage accurately.
Question 20.Why closed path is required for flow of current?
Answer:The closed path is necessary for electrons to move in a particular direction.
Question 21.What happens to the resistance of a conductor if the area of cross section is increased?
Answer:The resistance will decrease because the resistance has an in-direct relationship with the area.
Where, ρ is the constant (resistivity of the material)
Question 22.Why are copper and aluminium wires used for electrical transmission?
Answer:Both copper and aluminium are good conductors of electricity, hence they are employed for electrical transmission.
Question 23.What helps to maintain the potential difference across a conductor?
Answer:The cell (battery eliminator) maintains the potential difference across a conductor.
Question 24.Write one advantage of connecting devices in parallel and not in series.
Answer:In parallel connection, if one device fails to work, others will continue working as the potential difference across parallel connection is same.
Question 25.Give one difference between open circuit & closed circuit?
Answer:In open circuit, no current can flow across the circuit. Whereas, in closed circuit, continuous current flows.
What is zero error?
Answer:
If the pointer of the meter does not coincide with zero of the scale, this type of error in reading of the scale is called a Zero error.
Question 2.
What is least count?
Answer:
The smallest value that can be measured accurately by an instrument is called its least count.
Question 3.
Suppose the ammeter you are using in this experiment does not have positive and negative markings , How will you use such ammeter?
Answer:
We will connect the ammeter or Voltmeter arbitrary in the circuit and observe the deflection of the pointer. If the deflection occurs in the opposite direction then by interchanging the terminal connection, we can use these devices.
Question 4.
Suppose the deflection go beyond the full scale. What will you infer from such observation?
Answer:
If the deflection on ammeter goes beyond the full scale , we infer that:
1. The higher range ammeter has to be used to measure higher current.
2. The applied voltage is very high thus will require a high range voltmeter to measure applied voltage
Question 5.
Why it is advised to clean the ends of connecting wires before connecting them?
Answer:
It is advised to clean the ends of connecting wires to remove the insulating layer if any from to ends of the wire. Also, to remove any dust from the ends of the wire to ensure better flow of electrons in the junction.
Question 6.
While taking the reading the student observe that pointer on voltmeter is 15th division when voltmeter least count is 0.05V. Find the observed reading of voltmeter?
Answer:
Observed reading = Least count × Number of division
= 0.05 × 15
= 0.75 V
Question 7.
In a series combination, what happens to voltage and current?
Answer:
In series combination:
1. Current flowing across a different resistor connected in series are same
2. Voltage in a series is the sum of the voltage across the different resistor.
Question 8.
What is the equivalent resistance for a series combination & parallel combination?
Answer:
The equivalent resistance Req=R1+R2+…….+Rn.
The equivalent resistance in a parallel connection is given as:
Question 9.
In parallel combination, is the current same or voltage same in the circuit?
Answer:
In parallel combination:
1. The voltage across the resistor remains the same.
2. The current across the combination is the sum of the current across the different resistor.
Question 10.
Why are the standard resistances made up of manganin wire?
Answer:
The standard resistance coils are made up of manganin wire. The reasons are:
i. The variation of resistance with a rise in temperature is very less as compared to other metal.
ii. The resistivity of the material is very high & any resistance value can be made from it. Therefore, it is used as standard resistance.
Question 11.
What should be characteristics of standard resistance?
Answer:
1. The value of resistance should not change with time.
2. The value of resistance should almost remain the same with a change in temperature.
3. It should be convenient sizes.
Question 12.
Why connecting wires are made of copper?
Answer:
The connecting wires are made of copper because copper has low resistivity and it conducts the current without offering much resistance.
Question 13.
How many times will be the equivalent resistance of two identical resistors be increased if the parallel arrangement is changed to a series arrangement?
Answer:
The effective resistance in parallel combination is
That of series combination is Rs = 2R. Thus, we get Rs = 4Rp, i.e., equivalent resistance increases four times.
Question 14.
Can you distinguish between resistor and resistance?
Answer:
The resistor is a device which offers resistance, whereas resistance is the property of the resistor.
Question 15.
In what way household appliances should be connected?
Answer:
The household appliances should be connected in parallel in order to get equal voltage for each appliance and ensure that if one is a switch “on” or ”off,” others working are not affected.
Question 16.
Draw a diagram which shows the direction of current & the current carriers.
Answer:
The direction of current is from the positive terminal of the battery, it goes on through the components & then enters through negative terminal.
The current carriers are electrons and the motion of electrons is opposite from the electric current.
Question 17.
Why is ammeter always connected in series in a circuit?
Answer:
Ammeter is always connected in series with circuit as it should offer low resistance to the components added in the series. In this ways, the current can be measured accurately in low resistance.
Question 18.
Why is voltmeter always connected in parallel?
Answer:
Voltmeter should be connected in parallel because in parallel connection, the potential difference is same.
Question 19.
Which device has high resistance voltmeter or ammeter?
Answer:
Voltmeter has very high resistance and ammeter has negligible resistance. This is because when voltmeter is connected in parallel across any two points, it will draw very less current (due to high resistance), hence it can measure the voltage accurately.
Question 20.
Why closed path is required for flow of current?
Answer:
The closed path is necessary for electrons to move in a particular direction.
Question 21.
What happens to the resistance of a conductor if the area of cross section is increased?
Answer:
The resistance will decrease because the resistance has an in-direct relationship with the area.
Where, ρ is the constant (resistivity of the material)
Question 22.
Why are copper and aluminium wires used for electrical transmission?
Answer:
Both copper and aluminium are good conductors of electricity, hence they are employed for electrical transmission.
Question 23.
What helps to maintain the potential difference across a conductor?
Answer:
The cell (battery eliminator) maintains the potential difference across a conductor.
Question 24.
Write one advantage of connecting devices in parallel and not in series.
Answer:
In parallel connection, if one device fails to work, others will continue working as the potential difference across parallel connection is same.
Question 25.
Give one difference between open circuit & closed circuit?
Answer:
In open circuit, no current can flow across the circuit. Whereas, in closed circuit, continuous current flows.
