CBSE Class 12 Physics Viva Questions with Answers

CBSE class 12th exams are conducted in the second week of January 2026 (tentatively) offline, on a school level. It is one of the most important components of the CBSE class 12 Physics exam, with a total weightage of 20 marks. Examiners try to evaluate your knowledge of the theoretical concepts in a question-answer format. It requires you to thoroughly focus on concept-based answers, rather than lengthy explanations. 

CBSE Class 12 Physics viva questions consist of questions from topics like the Laws of Motion, Work, Energy and Power, Rotational Motion, etc. This page will help you get the complete list of CBSE class 12 Physics 2025-26 viva questions!

CBSE Class 12 Physics Viva Questions PDF Download

Check the link below for CBSE class 12 Physics viva questions 2026 with answers PDF:

CBSE Class 12 Physics Viva Questions with Answers 2025-26

CBSE Class 12 Physics Viva questions are based on all the important topics: Ohm’s law, Electricity, Reflection and refraction, Atmospheric refraction, Sources of energy, Chemical reaction and equation, Chemical properties of metals, Concave and convex mirrors, Magnetic field and Lens formula and magnification.

Q1. Define Ohm’s law. 

Ans. The current that flows through most conductors is directly proportional to the voltage applied. The voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperatures remain constant. 

Q2. What is the formula of Ohm’s law? 

Ans. Ohm’s law is given by the formula: V=IR, where I=current, V=voltage, and R=Resistance. 

Q3. What is specific resistance? 

Ans. The resistance offered per unit length and unit cross-sectional area when a known amount of voltage is applied is known as the specific resistance.

Q4. What is the SI unit of the potential difference? 

Ans. The SI unit of the potential difference is the volt.

Q5. The current is measured in what unit? 

Ans. The unit of electric current is the ampere.

Q6. What is the unit of resistance? 

Ans. The unit of electrical resistance is Ohms. 

Q7. Does the resistance depend on the temperature?

Ans. Yes, the resistance depends on the temperature. As the temperature increases, the resistance also increases.

Q8. What are the various sources of error while performing this experiment? 

Ans. Various sources of error are:

The instrument screws may be loose.

Lack of thick connecting wires.

Using a rheostat of high resistance. 

Q9. What is electrical conductivity? 

Ans. It is the measure of the ability of the material to allow the electric current to pass through it. 

Q10. Define a rheostat. 

Ans. A rheostat is a two-terminal electrical device. The rheostat is a variable resistor whose resistance can be changed to change the current flowing through a circuit. 

Q11. State true or false: The potential difference across the wire varies linearly with the current. 

Ans. True, the potential difference across the wire varies linearly with the current. 

Q12. Does the resistance depend on the dimensions of the conductor? 

Ans. Yes, the resistance depends on the dimensions of the conductor. 

Q13. Give one example of a substance whose resistance lowers with an increase in temperature. 

Ans. A semiconductor is the best example. 

Q14. How is a conductor’s resistance affected by an increase in temperature?

Ans. A conductor’s resistance increases when the temperature rises. 

Q15. How is an ammeter connected to an electric circuit? 

Ans. An ammeter is usually joined in series in the electric circuit. 

Q16. What is the main procedure to convert a galvanometer into an ammeter? 

Ans. A galvanometer is typically converted into an ammeter by linking a suitable low resistance wire (shunt) in parallel orientation with it. 

Q17. How are voltmeters attached to an electric circuit? 

Ans. Voltmeters are always connected in parallel. 

Q18. What is the main procedure to convert a galvanometer into a voltmeter? 

Ans. A galvanometer is typically converted into a voltmeter by linking a high resistance in series orientation with it. 

Q19. What is a potentiometer? 

Ans. A potentiometer is an electrical apparatus used for precise calculation of minute potential differences and to analyse the e.m.f.s of the available primary cells.

Q20. What is the difference between a scalar and a vector quantity?

Ans. A scalar quantity has only magnitude, while a vector quantity has both magnitude and direction.

Q21. What is the SI unit of force?

Ans. The SI unit of force is the newton (N).

Q22. What is Newton's second law of motion?

Ans. Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Q23. What is the difference between mass and weight?

Ans. Mass is the measure of the amount of matter in an object, while weight is the force of gravity acting on an object.

Q24. What is the principle of moments?

Ans. The principle of moments states that the sum of the moments of all the forces acting on a body is equal to zero.

Q25. What is the difference between work and power?

Ans. Work is the transfer of energy from one object to another, while power is the rate at which work is done.

Q26. What is the law of conservation of energy?

Ans. The law of conservation of energy states that energy cannot be created or destroyed, but it can be transformed from one form to another.

Q27. Which four precautions must be taken while experimenting to verify Ohm’s law?

Ans. (i) All connections should be kept tight.

(ii) The zero error in the ammeter and voltmeter should be noted down and taken into consideration while taking readings for the measurement.

(iii) The bare ends of the connecting wires should be rubbed and cleaned properly with sandpaper.

(iv) The value of the current through the circuit should be kept as low as possible to avoid heating of the resistor.

Q28. What is the difference between a conductor and an insulator?

Ans. A conductor is a substance that allows electricity to pass through it, while an insulator is a substance that does not allow electricity to pass through it.

Q29. What is the principle behind the experiment you performed to verify Ohm's law?

Ans. The voltage across a conductor is directly proportional to the current through it provided that all physical conditions and temperature remain the same.

Q30. What is the significance of the slope of the graph in the experiment to plot a graph of the dependence of potential difference across a resistor on current?

Ans. The slope of the straight line gives the resistance of the resistor.

Q31. How do you connect the resistors in series and in parallel in the experiment to find the equivalent resistance?

Ans. In a series arrangement, resistors are connected end-to-end, while in a parallel circuit, the terminals of resistors are connected to the same two nodes.

Q32. What is the difference between a series circuit and a parallel circuit?

Ans. In a series circuit, the components are connected in a line, one after the other, while in a parallel circuit, the components are connected in branches.

Q33. What is the difference between a convex lens and a concave lens?

Ans. A convex lens bends light rays towards each other, while a concave lens bends light rays away from each other.

Q34. What are the sources of error in the experiment you performed to determine the focal length of a convex mirror?

Ans. Two major sources of error are:

(i) The uprights are not ideally vertical.

(ii) The pole of the mirror, the tip of the object needle and the optical centre are not placed in a line.

Q35. What is the difference between a real image and a virtual image?

Ans. A real image is formed when light rays from an object converge at a point, while a virtual image is formed when light rays appear to diverge from a point but do not actually converge.

Q36. What is the difference between refraction and reflection of light?

Ans. Reflection is the bouncing back of light when it strikes a smooth surface. Refraction is the bending of light rays when it travels from one medium to another.

CBSE Class 12 Physics Viva Questions Preparation Tips

You should go through CBSE Class 12 Previous Year Question Papers to prepare along with CBSE class 12 Physics viva questions 2026 with answers PDF. These are some preparation tips that you must also keep in mind:

• Review the entire CBSE class 12th physics syllabus. Pay close attention to the topics that are likely to be covered in the CBSE class 12 physics practical viva questions.
• Focus on key concepts and definitions. Ensure you can explain them clearly and concisely.
• Practice answering questions aloud. This will help you improve your communication skills and build confidence.
• Ask a friend or family member to act as the examiner. This will simulate a real viva situation.
• Review your answers and identify areas for improvement.
• Read science magazines and articles. This will help you stay updated on current scientific discoveries and advancements.
• Watch science documentaries and videos. This will provide you with a better understanding of complex concepts..

Best Books for CBSE Class 12 Physics Viva Questions 2025-26

The best books for physics viva questions class 12 CBSE 2026 are listed below:

1. S Chand's books for class XII
2. Pradeep's publication, Fundamentals of Physics class XII (Vol I+Vol II)

CBSE Class 12 Physics Viva Questions Marking Scheme

The CBSE Class 12 Physics Viva Questions are worth a total of 20 marks. The total marks are divided into various components. The marking scheme for class 12 physics viva questions with answers is explained below:

By following these tips, you can effectively prepare for your CBSE Class 12 Physics viva and increase your chances of success.