CBSE Class 12 Physics Competency-Based Questions With Answer Key 2024-25: Chapter 2 Current Electricity FREE PDF Download

CBSE 2024-25 Competency-Based Questions With Answers: The Central Board of Secondary Education (CBSE) has released  the competency-focused practice questions for the 2024-25 academic year, covering key subjects for both Class 10 and Class 12.  By practicing these questions, students can better familiarise themselves with the format and style of questions likely to appear in the actual exams, improving their confidence and performance. These questions are organised chapter-wise across three volumes per subject. 

Specifically, for Class 12 Physics, Chapter 2 on Current Electricity, the CBSE has provided competency-based questions designed to enhance understanding and application skills for the 2025 exams. The FREE PDF files include both multiple-choice questions (MCQs) and free-response questions, which are available for download.

CBSE Class 12 Physics Chapter 2 Competency-Based Questions

Question 1:  If  the  voltmeter  in  the  given  circuit  reads  8  V,  what  is the resistance of the voltmeter?  

1. 70/4119 Ω 
2. 70 Ω 
3. 420 Ω 
4. 4200 Ω 

Question 2: Which combination of the three resistors will dissipate maximum power from a  10 V battery? 

1. II 
2. III 
3. IV

Question 3: If  the  ammeter  reading  in  the  given  circuit  is  zero,  find  the  value  of  the  resistance R.

1. 50 ohm 
2. 100 ohm 
3. 150 ohm 
4. 200 ohm 

Check: Ohm’s Law: Definition, Statement, Application And Limitations

Question 4: Resistances 10 Ω and R Ω are connected in the two gaps of a metre bridge. The null point is obtained at 30 cm on the metre scale from the zero end. What resistance must be connected in parallel to R so that the null point is at the mid‐point of the metre wire? 

1. 10 Ω 
2. 70/3 Ω 
3. 70/4 Ω 
4. 3/70 Ω 

Question 5: Accelerated  alpha  particles,  constituting  a  beam  current  of  0.64  mA,  are  released by a cyclotron onto a target. Find the number of alpha particles that  strike the target in one second. 

Question 6:  Alloys  like  Nichrome,  whose  temperature  coefficient  of  resistance  is

 ~ 0.4 x 10^‐3 /^o C at 20^o C, are used widely in the making of wire‐bound standard  resistors as their resistance changes very little with changes in temperature.  

(i) Find the temperature at which the resistance of a given Nichrome wire would  be reduced to half its value at 20oC. 

(ii) State an anomaly regarding the temperature value obtained in (i). 

Question 7:  A battery of 6 V drives a current of 60 mA through an electric lamp. Another  battery of 10 V drives a current of 70 mA through the same lamp. Is the lamp an  ohmic device? Explain. 

Question 8:  A dimmer is a device that is connected to a light bulb and is used to lower the  brightness of the light from the bulb. It introduces a resistance in series with the  bulb for this purpose. A 44 W bulb in a household circuit is connected across a  220 V power supply. 

(a) How much current does the bulb draw initially without the dimmer in action? 

(b) What  resistance in series would  the dimmer introduce in order  to drive a  current of 0.1 A through this bulb? 

Question 9:  Eva needs a 3 V power supply for her electronic circuit experiment. There is a  10 V battery in the lab that she can use. Eva decides to make a voltage divider  using this battery and two different resistors, the larger value resistor being 300  ohm.  What value of the smaller resistor should Eva use to make the desired voltage divider?

Question 10:  A flashlight uses two batteries, each of emf 2 V and internal resistance 0.1 ohm,  in series. The flashlight bulb has a resistance of 10 ohm. 

(a) What is the current drawn by the flashlight bulb? 

(b) How much power is dissipated through the flashlight bulb? 

(c) If the two batteries have zero internal resistances, will the power dissipated through the flashlight bulb be more or less? Calculate the difference. 

Question 11:  In order to discourage the use of personal electrical appliances by the guests in  the rooms of a motel in a small town, each 220 V socket in the room is wired  with a circuit breaker on a 5 A line.  Sam wishes to iron his clothes using his 1200 W, 220 V portable steam iron box  2  in his motel room. 

(a) Will Sam be able  to use his iron box without  tripping  the circuit breaker?  Explain. 

(b) Find the resistance of his iron box. 

Question 12:  Tim is a music enthusiast who wishes to create good sound effects for his stereo  system using his two sets of speakers at home.  The first set consists of two speakers of resistance 10 Ω each. The second  set  consists  of  two  speakers  with  resistances  5 Ω  and  10 Ω  respectively.  Initially,  he  connects  the  first  set  of  two  10 Ω  speakers in  series  to  the  10 V  stereo output.  Later, he connects the second set of speakers such that each of them is parallel  to the first set of speakers.  

(a) What is the current through each of the 10 Ω speakers BEFORE the second  set of speakers were connected?  

(b) What  is  the  new  current  through  each  of  the  10 Ω  speakers  AFTER  the  second set of speakers are connected?  

(c) If the loudness of the music is directly proportional to the amount of power  used by the speaker, how has the loudness of the first set of speakers changed  due to the introduction of the second set of speakers?  

(d) What is the impact of connecting the second set of speakers in the circuit  here?

Question 13: Rene uses a portable electric lamp to light up her keyboard when working on  her computer at night. The lamp consists of two small bulbs each of resistance  2 ohm connected in series and is powered by a 20 V battery. 

(a) How much current is drawn by the portable lamp? 

(b) Each of the two bulbs in the portable lamp is rated for continuous use of 10  hours only before they burn out. If the battery can supply total energy of 4000  kJ, which of the two occurs first: the lamp burns out or the battery drains out? Show the working. 

Question 14: In the given network of resistors, the 16‐ohm resistor burns out as soon as it  begins to dissipate 100 W of power.  

What MAXIMUM voltage can be applied across terminals A and B, in order to  avoid the burn out of the 16‐ohm resistor? 

Question 15:  Determine the equivalent resistance of the following combination of resistors.  Show the working (include diagrams if required). 

Question 16:  A Wheatstone’s bridge employs 5 resistors as shown. Find the value of n that  will ensure that the bridge is always in a balanced condition, irrespective of the  value of r. 

 

Question 17: Determine  the  value  of  R  in  the  given  network  for  each  of  the  conditions  separately. 

1. If VB – VD = 8 V 
2. If VA ‐ VC = 8 V

To access all the practice question of Physics Chapter 2 Current Electricity, the complete FREE PDFs are attached here. Click on the 'Download PDF' to get the PDF.

CBSE Class 12 Physics Competency-Based Questions With Answer Key 2024-25

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Preparing for board exams can be challenging, but with right strategies and techniques you can approach your studies in right direction. Here are some tips which will help you to prepare for board exams: 

• Create a Study Plan: Making study plan befor exam will beneficial for students. Break your syllabus into small sections as per your comfort level and allocate time for each subject based on its difficulty and your comfort level with it.
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• Use Quality Study Materials: Rely on NCERT or prescribed textbooks as they are usually the basis for board exams. Use additional reference books and guides for more in-depth understanding if necessary.
• Practice Past Papers: Practice last year board exam sample papers to get a feel for the types of questions asked and the exam format. Take timed mock tests to improve your speed and accuracy.
• Focus on Conceptual Understanding: Ensure you understand the concepts thoroughly rather than just memorising facts.
• Regular Revision: Regularly revise what you've studied to brushup your memory. Make concise notes for quick revision of key points.
• Manage Stress: Practice stress management techniques like deep breathing, meditation, or light exercise. Take regular breaks during study sessions to avoid burnout.
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By following these tips, you can improve your preparation for board exams and increase your chances of achieving your desired results.