4. To determine the equivalent resistance of two resistors when connected in series.practicals anwers
Answers
Answer:
formula
Explanation:
R=R1+R2+R3+upto+Rn
Answer:
In a series connection, the current flows through one resistor and then the other. The current flowing through each resistor is the same as the current flows in one direction. The total voltage is the sum of all the voltage drops across the resistors. There are few drawbacks of a series circuit, and they are:
• Either because of the overflow of current or loss of current, short-circuiting may happen.
• The electrical appliance may be damaged due to a high flow of current.
• Only one device cannot be switched off, without turning off both the devices.
Aim
To determine the equivalent resistance of two resistors when connected in series.
Theory
Depending on the combination and connections in a circuit, the resistance can be increased or decreased. The difference between the series and parallel circuit is based on the arrangement of the resistors. Resistors are said to be connected in series if their ends are joined. The potential difference across each resistor would be different but the current would be the same.
If two resistors are connected in series then;
Resistance, R = R1+R2
Current, I = constant
Potential difference, V = V1+V2
On applying Ohm’s law, we get,
V1 = IR1
V2 +IR2
V = V1+V2
V = I(R1+R2)
∴ R = R1+R2
Materials Required
• Two resistors of different values
• A battery of 6 volts
• Ammeter
• Plug key
• Connecting wires
• A piece of sandpaper
• Voltmeter
• Rheostat
Circuit Diagram
check attachment
Procedure
1. With the help of circuit diagram, make the connections.
2. Do not switch on the key.
3. The ammeter should be connected in series, voltmeter in parallel, and the rheostat in series.
4. Make the connections as shown in the experimental setup and check of +ve and -ve terminals of the battery.
5. By inserting the key, record the ammeter and voltmeter readings.
6. Note three readings by adjusting the rheostat.
7. Note down the readings of a voltmeter by connecting it to each resistor.
8. Measure the potential difference, V1 across the first resistor by plugging in the key.
9. Measure the potential difference, V2 across the second resistor by plugging in the key.
10. Calculate the relationship between V, V1, and V2.
Observation Table
check attachment
Result
check attachment
Precautions
1. Voltmeter and resistor should always be in parallel.
2. The least count of voltmeter and ammeter should be calculated properly.
3. Connections should be as per the experimental setup.
4. When no current flows through the ammeter and voltmeter, the pointers should be at zero mark.
5. The connecting wires that are used should be thick copper wire and using sandpaper the insulation at the end of the wires should be removed.
6. To avoid the introduction of external resistance, the connections should be tight.
7. To avoid heating and change in the resistance value of the resistor, the current should flow while taking the readings.
Explanation:
some questions
Q1. What will be the total resistance of two resistors connected in series with value 2 Ω and 3 Ω?
Ans: The total resistance is given as:
R = R1 + R2
∴ R = 2 Ω + 3 Ω = 5 Ω
Q2. Determine the voltmeter reading for a series circuit if a current of 5A is flowing through 2 Ω and 3 Ω resistors.
Ans: The voltmeter reading across the 2 Ω resistor is given as:
V =IR
V1= 5 × 2 = 10V
The voltmeter reading across the 3 Ω resistor is given as:
V =IR
V2= 5 × 3 = 15V
∴ V = V1+V2
V = 10 + 15 = 25V
Q3. How should the resistor be connected so that the resultant resistance is increased?
Ans: To get the resultant resistance maximum, the resistors should be connected in series.
Q4. What will be the total resistance if two equal resistors are connected in series?
Ans: If two equal resistors are connected in series, then the total resistance is given as:
R + R = 2R.
Q5. Where should the voltmeter be connected when the resistors are in series?
Ans: The voltmeter should be connected parallel when the resistors are in series.
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