- Home |
- Board Exams|

NCERT Exemplar Solutions for Class 12 Physics Chapter 7 Alternating Current are available here. In this article, you will get solutions of long answer type questions (i.e. question number 7.21 to 7.26).

We have already provided solutions of multiple choice questions with single correct answer (MCQ I), multiple choice questions with multiple correct answers (MCQ II), very short answer type questions (VSA) and short answer type question (SA). You can access them from links given below

**NCERT Exemplar Solutions for Class 12 Physics - Chapter 7: Alternating Current (MCQ I)**

**NCERT Exemplar Solutions for Class 12 Physics - Chapter 7: Alternating Current (MCQ II)**

**NCERT Exemplar Solutions for Class 12 Physics - Chapter 7: Alternating Current (VSA)**

**NCERT Exemplar Solutions for Class 12 Physics - Chapter 7: Alternating Current (SA)**

**NCERT Exemplar Solutions for CBSE Class 12 Physics, Chapter 7 (from question number 7.27 to 7.31) are given below:**

**Question 7.27:**

**Solution 7.27:**

**Question 7.28:**

1MW power is to be delivered from a power station to a town 10 km away. One uses a pair of Cu wires of radius 0.5 cm for this purpose. Calculate the fraction of ohmic losses to power transmitted if

(i) power is transmitted at 220V. Comment on the feasibility of doing this.

(ii) a step-up transformer is used to boost the voltage to 11000 V, power transmitted, then a step-down transformer is used to bring voltage to 220 V.

(ρ* _{Cu}* = 1.7 × 10

**Solution 7.28:**

**Question 7.29:**

Consider the LCR circuit shown in Fig 7.6. Find the net current i and the phase of i. Show that i = v/Z. Find the impedance Z for this circuit.

**Solution 7.29:**

**Question 7.30:**

For an LCR circuit driven at frequency ω, the equation reads

*L *(*di*/*dt*) + *Ri* + *q*/*C* = *v _{i}* =

(*i*) Multiply the equation by *i* and simplify where possible.

(*ii*) Interpret each term physically.

(*iii*) Cast the equation in the form of a conservation of energy statement.

(*iv*) Intergrate the equation over one cycle to find that the phase difference between v and i must be acute.

**Solution 7.30:**

**Question 7.31:**

In the LCR circuit shown in Fig 7.7, the ac driving voltage is *v* = *v*_{m} sin *ωt*.

(*i*) Write down the equation of motion for *q* (*t*).

(*ii*) At *t* =* t _{}*, the voltage source stops and R is short circuited. Now write down how much energy is stored in each of L and C.

(*iii*) Describe subsequent motion of charges.

**Solution 7.31**

**NCERT Solutions for CBSE Class 12 Physics: All Chapters**

- About CBSE Exam
- CBSE Class 9
- CBSE Alerts | Results
- CBSE Class 10
- CBSE Class 11
- CBSE Class 12
- CBSE Study Material
- CBSE Sample Papers
- UP Board
- CBSE Question Papers
- Jharkhand Board
- Gujarat Board
- CBSE Date Sheet
- Rajasthan Board
- Bihar Board
- Uttarakhand Board
- West Bengal Board
- Himachal Pradesh Board
- Tamil Nadu Board
- CBSE Syllabus
- Madhya Pradesh Board
- Orissa Board
- Andhra Pradesh Board
- Chhattisgarh Board
- CBSE Result
- Assam Board
- CBSE QnA
- CBSE Mock Papers
- More In CBSE
- What? Why? How?

- Rajasthan Board Class 12th Geography Model Question Paper: Marking Scheme, Weightage and Blueprint
- Rajasthan Board Class 12th Hindi Model Question Paper: Marking Scheme, Weightage and Blueprint
- Rajasthan Board Class 10 Social Science Syllabus
- CBSE Class 10 Science NCERT Solutions: Chapter 8, How Do Organisms Reproduce?
- CBSE Class 10 Science NCERT Solutions: Chapter 7, Control and Coordination

- NCERT Solutions for CBSE Class 10 Maths: All Chapters
- CBSE Class 9 Mathematics NCERT Solution: Chapter 2, Polynomials
- CBSE Class 9 Mathematics NCERT Solutions: Chapter 6, Lines and Angles
- CBSE Class 9 Mathematics NCERT Solutions: Chapter 7, Triangles
- CBSE Class 9 Mathematics NCERT Solutions: Chapter 12, Heron’s Formula

Must Read