CBSE Class 12 Physics Solved Question Paper 2018

Solved question paper of CBSE 12th Physics board exam 2018 is available here for download in PDF format. Students can also download the complete paper with the help the download link. CBSE Class 12 Physics board exam 2018 was held on March 7, 2018 from 10.30 A.M. to 1.30 PM. More than 5 lakh students of CBSE Class 12 having Physics as one of their subjects appeared for this paper. The duration of the paper was 3 hours and it carried a total of 70 marks.

Many students who took the Physics paper emerged from the hall upset and disappointed. Students claimed that the paper was very lengthy. Demanding lenient marking for CBSE Class 12 Physics paper 2018, students have started an online petition and more than 60000 students have signed the petition.

According to our subject experts, in fact, Class 12 Physics paper was lengthy. Out subjects experts, papers have solved the complete question paper. Now anyone can easily check and analyse whether the paper was lengthy or not. With the help of this completely solved Physics paper of CBSE Class 12 Board exam 2018, students can easily crosscheck their solutions. They can also calculate the expected score.

We have collected feedback from students and teachers. You can read the complete analysis of CBSE Class 12 Physics board exam 2018 from the link given below

CBSE Class 12 Physics Board Exam 2018 - Paper analysis

General Instructions given CBSE Class 12 Physics Question Paper 2018:

 All questions are compulsory. There are 26 questions in all. This question paper has five sections - Section A, Section B, Section C, Section D and Section E. Section A contains five questions of one mark each, Section B contains five questions of two marks each, Section C contains twelve questions of three marks each, Section D contains one value based question of four marks and Section E contains three questions of five marks each. There is no overall choice. However, an internal choice has been provided in one question of two marks, one question of three marks and all the three questions of five marks weightage. You have to attempt only one of the choices in such questions. You may use the following values of physical constants wherever necessary: c = 3 × 108 m/s h = 6.34 × 10‒34 Js e = 1.6 × 10‒19 C μo = 4π × 10‒7 T m A‒1 εo = 8.854 × 10‒12 C2 N‒1 m‒2 {1/(4π εo)} = 9 × 109 N m2 C‒2 Mass of electron = 9.1 ×10−31 kg Mass of neutron = 1.675 ×10−27 kg Mass of proton = 1.673 ×10−27 kg Avogadro's number = 6.023 ×1023 per gram mole Boltzmann constant = 1.38 ×10−23 JK−1

Some questions and answers from the paper are given below:

Question:

Name the electromagnetic radiations used for (a) water purification, and (b) eye surgery.

Solution:

(a) Ultraviolet rays

(b) Infrared rays

Question:

Four nuclei of an element undergo fusion to form a heavier nucleus, with release of energy. Which of the two - the parent or the daughter nucleus - would have higher binding energy per nucleon?

Solution:

The binding energy per nucleon of the fused heavier nuclei is more than the binding energy per nucleon of the lighter nuclei. So, binding energy is more per nucleon in daughter nuclei.

Question:

Which mode of propagation is used by short wave broadcast services?

Solution:

In the frequency range from a few MHz up to 30 to 40 MHz, long distance communication can be achieved by ionospheric reflection of radio waves back towards the earth. This mode of propagation is called sky wave propagation and is used by short wave broadcast services.

Question:

Two electric bulbs P and Q have their resistances in the ratio of 1 : 2. They are connected in series across a battery. Find the ratio of the power dissipation of these bulbs.

Solution:

For series combination, power dissipated by a bulb is directly proportional to its resistance.

P ∝ R

P1/P2 = R1/R2 = 1/2.

Question:

(a) Why are infra-red waves often called heat waves? Explain.

(b) What do you understand by the statement, "Electromagnetic waves transport momentum"?

Solution:

(a) Infrared waves often called heat waves because water molecules present in most materials readily absorb infrared waves (many other molecules, for example, CO2, NH3, also absorb infrared waves). After absorption, their thermal motion increases, that is, they heat up and heat their surroundings.

(b) It means when these waves strike a surface, a pressure is exerted on the surface.

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