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Current Electricity

Home / Boards / CBSE / Important Questions / Class 12 / Physics / Current Electricity

Class 12 Physics Chapter 3
Current Electricity
Important Questions

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Mastering a variety of question formats on ‘Current Electricity’ is essential for class 12 syllabus. These curated class 12 physics current electricity important questions and answers serve as a valuable tool for comprehensive preparation. They offer students an opportunity to tackle uncertainties, bolster confidence, and refine their problem-solving skills. By delving into these current electricity class 12 important questions students can strengthen their understanding of the most significant concepts within the topic. These current electricity imp questions aim to solidify knowledge on current electricity, ensuring students approach the exam with assurance and proficiency.”

Introduction

“Current Electricity” represents an enthralling chapter in Class 12 Physics, delving deep into the fascinating realm of electrical phenomena and their practical implications. This section navigates through fundamental concepts such as electric current, Ohm’s law, resistors, circuits, and their intricate relationships. Mastery of these principles isn’t just crucial theoretically but holds immense practical significance across diverse technological domains. The chapter unravels the complexities of current flow, resistance, power dissipation, and forms the backbone of modern electronics. Through exploration of current electricity important questions we aim to gain comprehensive insight into this pivotal chapter.

What are Current Electricity?

Current Electricity is the study of how electric charges move through conductors. It’s the flow of electrons in a closed pathway, powering devices and enabling the transfer of energy. This topic explores how electric current behaves in circuits, the impact of resistance on this flow, and the relationships between voltage, current, and resistance as defined by Ohm’s law. Mastering this concept involves understanding the dynamics of electrical circuits and how they facilitate the movement of charge to power various appliances and technologies. oswal.io provides class 12th physics chapter 3 important questions which can help you in preparing for examination.

Class 12 Physics Current Electricity Important Questions and Answers

Q1. An iron cored coil is connected in series with an electric bulb with an AC source as shown in figure. When iron piece is taken out of the coil, the brightness of the bulb will:
original 1
Options
(a) decrease
(b) increase
(c) remain unaffected
(d) fluctuate

Ans. (b) increase

Explanation:
As the iron rod is removed from the coil, the coil’s self-inductance falls, the circuit’s impedance drops and the current rises as a result. Therefore, the electricity used by the bulb grows, as does the brightness of the bulb.

Q2. Ohm’s law deals with the relation between:
Options
(a) current and potential difference
(b) capacity and charge
(c) capacity and potential
(d) charge and potential difference

Ans. (a) current and potential difference
Explanation: Ohm’s law deals with the relation between current and potential difference.
i.e., V∝ I
V = IR

Q3. A toaster produces more heat than a light bulb when connected in parallel to the 220 V mains. Which has a greater resistance ?

Explanation:
The amount of heat produced by an electric current in time t is given by \\ \text{H = -I}^2\text{Rt} = \dfrac{\text{V}^2\text{t}}{\text{R}} \\[4.5 bp] \text{i.e. }\space \space \space \text{H ∝ } \dfrac{1}{\text{R}}\\ For the parallel combination, potential difference V is same. As toaster produces more heat,has lower resistance.So The light bulb, which produces less heat, has greater resistance.

Q4. The variation of the resistance of a metallic conductor with temperature is shown in figure.
resistance
(i) Calculate the temperature coefficient of resistance from the graph.
(ii) State why the resistance of the conductor increases with the rise in temperature.

Explanation:
(i) Temperature Coefficient of Resistance (α):
The resistance at 0°C is \text{R}_0 and the resistance at temperature θ is R.
The change in resistance is \text{R−R}_0 and the change in temperature is θ−0 = θ.
The temperature coefficient of resistance is given by:
\alpha = \dfrac{\text{change in resistance}}{\text{original resistance × change in temperature}}\\[4.5 bp] = \dfrac{\text{R - R}_0}{\text{R}_0 × \theta} \\ This equation can also be expressed geometrically using the graph as:
\alpha = \dfrac{\text{OC - OA}}{\text{OA × OE}}\\ (ii) The resistance of a metallic conductor increases with a rise in temperature because, as temperature increases, the thermal energy of the metal ions increases. This causes the ions to vibrate more, which increases the likelihood of collisions between conduction electrons and ions. As a result, the motion of electrons is hindered, leading to an increase in resistance.

Q5. Why is the terminal voltage of a cell less than its emf ?

Explanation:
EMF = Terminal potential difference + potential difference across internal resistance
ε = V + Ir
A real cell has always some internal resistance, a part of the emf is consumed in doing work against the internal resistance in a closed circuit.
So ε > V or V < ε.

CBSE Class 12 Physics Chapter wise Important Questions

Chapter No.Chapter Name
Chapter 1Electric Charges and Fields
Chapter 2Electrostatic Potential and Capacitance
Chapter 3Current Electricity
Chapter 4Moving Charges and Magnetism
Chapter 5Magnetism and Matter
Chapter 6Electromagnetic Induction
Chapter 7Alternating current
Chapter 8Electromagnetic Waves
Chapter 9Ray Optics and Optical Instruments
Chapter 10Wave Optics
Chapter 11Dual Nature of Radiation and Matter
Chapter 12Atoms
Chapter 13Nuclei
Chapter 14Semiconductor Electronics: Materials, Devices and Simple Circuits

Conclusion

Understanding the foundational principles of how charged particles interact within their environment is key to grasping Current Electricity in Class 12 Physics. Platforms such as oswal.io offer important questions of current electricity class 12 supporting comprehensive learning and preparation in mastering this essential aspect of electrical science.

Frequently Asked Questions

Ans: Electric current is the flow of electric charge. In a conductor, it’s the movement of electrons in a particular direction, typically within a closed circuit.
Ans: Ohm’s Law states the relationship between voltage (V), current (I), and resistance (R) in a circuit: V = I * R. It shows that voltage is proportional to the product of current and resistance.
Ans: Resistance is a measure of how much a material opposes the flow of electric current. Higher resistance reduces the flow of current in a circuit, leading to a decrease in the current.
Ans: Series circuits have components arranged in a single path, so the same current flows through each component. In parallel circuits, components are connected across multiple paths, allowing different currents to flow through each component.
Ans: DC flows in one direction consistently, as in batteries, while AC alternates direction periodically, as in household electricity. AC is more suitable for long-distance transmission due to its ability to change voltage levels easily.
Chapter Wise  Important Questions for CBSE Board Class 12 Physics
Electric Charges and Fields
Electrostatic Potential and Capacitance
Current Electricity
Moving Charges and Magnetism
Magnetism and Matter
Electromagnetic Induction
Alternating current
Electromagnetic Waves
Ray Optics and Optical Instruments
Wave Optics
Dual Nature of Radiation and Matter
Atoms
Nuclei
Semiconductor Electronics: Materials, Devices and Simple Circuits
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