NCERT solutions for class 12 physics chapter 3 Current Electricity- Current is the flow of electric charge through a given area. If we want to utilize the charge flow we must have a closed path. Solutions of NCERT class 12 physics chapter 3 current electricity explains questions about the factors affecting the current flow, how current is flowing in a conductor, basic laws related to current electricity and circuit analysis and a few measuring devices. The solutions of NCERT will help you boost your knowledge. CBSE NCERT solutions for class 12 physics chapter 3 current electricity explains questions related to Ohm’s law and Kirchoff's law which will help in solving circuit related problems in exams. The chapter also gives an idea about ammeter, voltmeter, potentiometer, whetstones bridge and meter bridge. The NCERT solutions for class 12 physics chapter 3 current electricity also explains problems related to heat developed in a resistor.
NCERT solutions for class 12 physics chapter 3 Current Electricity Exercise:
3.3 (a) Three resistors 1 Ω, 2 Ω, and 3 Ω are combined in series. What is the total resistance of the combination?
We know that when resistors are combined in series, the effective resistance is the sum of that resistance.
Hence, total resistance of the three resistance combination = 1 + 2 + 3 = 6
3.3 (b) If the combination is connected to a battery of emf 12 V and negligible internal resistance, obtain the potential drop across each resistor.
Since the resistances are in series, the current through each one of them will be equal to the current through the circuit but voltage/ potential drop will be different.
Total resistance, R = 6
Emf, V = 12 V
According to Ohm's law:
V = IR
12 = I x 6
I = 12/6 = 2 A
Now, using the same relation, voltage through resistors:
1 : V(1) = 2 x 1 = 2V
2 : V(2) = 2 x 2 = 4V
3 : V(3) = 2 x 3 = 6V
(Note: V(1) + V(2) + V(3) = 2 + 4 + 6 = 12 V )
3.4 (a) Three resistors 2 Ω, 4 Ω and 5 Ω are combined in parallel. What is the total resistance of the combination?
We know that when resistances are in parallel combination, the total resistance R is given by:
Therefore, total resistance of the given three resistances in parallel combination is
Hence, the total resistance is 1.05
Let current in the circuit is distributed like
where I1, I2, and I3 are the different current through shown branches.
Now, applying KVL in Loop
Also, we have
so putting it in kvl equation
Now let's apply kvl in the loop involving I1 I2 AND I3
now, the third equation of KVL
Now we have 3 equation and 3 variable, on solving we get
Now the total current
3.11 A storage battery of emf 8.0 V and internal resistance 0.5 Ω is being charged by a 120 V dc supply using a series resistor of 15.5 Ω. What is the terminal voltage of the battery during charging? What is the purpose of having a series resistor in the charging circuit?
Emf of battery, E = 8 V
Internal resistance of battery, r = 0.5 Ω
Supply Voltage, V = 120 V
The resistance of the resistor, R = 15.5 Ω
Let V' be the effective voltage in the circuit.
Now, V' = V - E
V' = 120 - 8 = 112 V
Now, current flowing in the circuit is:
I = V' / (R + r)
Now, using Ohm ’s Law:
Voltage across resistor R is v = IR
v = 7 x 15.5 = 108.5 V
Now, the voltage supplied, V = Terminal voltage of battery + v
Terminal voltage of battery = 120 -108.5 = 11.5 V
The purpose of having a series resistor is to limit the current drawn from the supply.
(a) Determine the equivalent resistance of networks shown in
It can be seen that in every small loop resistor 1 ohm is in series with another 1 ohm resistor and two 2 ohms are also in series and we have 4 loops,
so equivalent resistance of one loop is equal to the parallel combination of 2 ohms and 4 ohm that is
now we have 4 such loops in series so,
Hence equivalent resistance of the circuit is 16/3 ohm.
NCERT Solutions for Class 12 Physics - Chapter Wise
Subject wise solutions-
Importance of solutions of NCERT for class 12 chapter 3 current electricity in board exams:
As far as the CBSE board exam and competitive exams are considered the solutions of class 12 NCERT chapter 3 current electricity is important. In NEET and JEE Main previous year papers 7 to 10% questions are asked from this chapter. In 2019 CBSE board exam 6 marks questions are asked from current electricity. Learn CBSE NCERT solutions for class 12 physics chapter 3 current electricity for a better score in board and competitive exams.