# Conceptual Questions for Class 12 Physics Chapter 1 Electric Charges and Fields

## Conceptual Questions for Class 12 Physics Chapter 1 Electric Charges and Fields

In this article we are providing conceptual questions for class 12 physics chapter 1 Electric Charges and Fields. Students are suggested to go through each and every question to understand the chapter well.

Q.1. Is the mass of a body affected on charging?

Solution. Yes. Electrons have a definite mass. The mass of a body slightly increases if it gains electrons while the mass decreases if the body loses electrons.

Q.2. Can two like charges attract each other? If yes, how?

Solution. Yes. If one charge is larger than the other, the larger charge induces equal and opposite charge on the nearer end of the body with smaller charge. The opposite induced charge is larger than the small charge initially present on it.

Q.3. A positively charged rod repels a suspended object. Can we conclude that the object is positively charged?

Solution. Yes, the object is positively charged. Repulsion is the surest test of electrification.

Q.4. A comb run through one’s dry hair attracts small bits of paper. Why? What happens if the hair is wet or if it is a rainy day?

Solution. When the comb runs through dry hair, it gets charged by friction. The molecules in the paper get polarized by the charged comb, resulting in a net force of attraction. If the hair is wet, or if it is rainy day, friction between hair and the comb reduces. The comb does not get charged and thus it will not attract small bits of paper.

Q.5. An electron and a proton are kept in the same electric field. Will they experience same force and have same acceleration?

Solution. Both electron and proton will experience force of same magnitude, F = eE. Since a proton has 1836 times more mass than an electron, so its acceleration will be 1/1836 times that of the electron.

Q.6. Why do the electrostatic field lines not form closed loops?

Solution. Electrostatic field lines start from a positive charge and end on a negative charge or they fade out at infinity in case of isolated charges without forming any closed loop.

Alternatively, electrostatic field is a conservative field. The work done in moving a charge along a closed path must be zero. Hence, electrostatic field lines cannot form closed loops.

Q.7. An arbitrary surface encloses a dipole. What is the electric flux through this surface?

Solution. As the total charge of a dipole is zero, so by Gauss’s theorem, the electric flux through the closed surface is zero.

Q.8. The electric lines of force tend to contract lengthwise and expand laterally. What do they indicate?

Solution. The lengthwise contraction indicates attraction between unlike charges while lateral expansion indicates repulsion between like charges.

Q.9. Why is electric field zero inside a charged conductor?

Solution. This is because charges reside on the surface of a conductor and not inside it.

Q.10. Why should a test charge be of negligibly small magnitude?

Solution. The magnitude of the test charge must be small enough so that it does not disturb the distribution of the charges whose electric field we wish to measure otherwise the measured field will be different from the actual field.

## Importance of conceptual questions for class 12 physics

Conceptual questions are of utmost importance in Class 12 Physics for several reasons. These questions focus on understanding the fundamental principles and concepts rather than just rote memorization of equations and formulas. Here are some reasons why conceptual questions are crucial in Class 12 Physics:

1. Deep understanding: Conceptual questions require students to grasp the underlying principles and theories behind physical phenomena. This leads to a deeper understanding of the subject, making it easier to apply the knowledge to various problem-solving scenarios.
2. Critical thinking: When students tackle conceptual questions, they are encouraged to think critically and analytically. These questions often involve complex scenarios that demand logical reasoning and creative thinking to arrive at the right answers.
3. Problem-solving skills: Conceptual questions challenge students to solve unfamiliar and intricate problems. As a result, their problem-solving skills are honed, preparing them to tackle more advanced scientific challenges in the future.
4. Application of concepts: By answering conceptual questions, students learn to apply theoretical concepts to practical situations. This bridges the gap between theory and real-world applications, fostering a holistic understanding of Physics.
5. Better exam preparation: Class 12 board exams and competitive entrance exams often include conceptual questions. Preparing for such questions not only improves performance in exams but also sets a strong foundation for further studies in physics-related fields.
6. Enhanced retention: Understanding concepts leads to better retention of knowledge. Unlike rote memorization, conceptual understanding stays with students for a long time, making it easier to build on that knowledge in the future.
7. Encouraging curiosity: Conceptual questions often pique students’ curiosity and encourage them to explore the subject further. This can spark an interest in Physics as a whole, leading to a lifelong passion for the subject.
8. Formulating connections: Conceptual questions help students make connections between different topics and subfields within Physics. This interconnected knowledge is essential for a comprehensive understanding of the subject.
9. Learning from mistakes: When students attempt conceptual questions, they may make mistakes. However, these mistakes provide valuable learning opportunities, as they highlight areas that need further clarification and understanding.
10. Building confidence: Successfully answering conceptual questions gives students a sense of accomplishment and boosts their confidence in their Physics abilities.

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