# Class 12 Physics Chapter 3 Case Study Question Current Electricity PDF Download

In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Download of CBSE Class 12 Physics Chapter 3 Current Electricity Case Study and Passage Based Questions with Answers were Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Physics Current Electricity to know their preparation level.

In CBSE Class 12 Physics Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

# Current Electricity Case Study Questions With answers

Here, we have provided case-based/passage-based questions for Class 12 Physics Chapter 3 Current Electricity

Case Study/Passage-Based Questions

Question 1:

Emf of a cell is the maximum potential difference between two electrodes of the cell when no current is drawn from the cell. Internal resistance is the resistance offered by the electrolyte of a cell when the electric current flows through it. The internal resistance of a cell depends upon the following factors;
(i) distance between the electrodes
(ii) nature and temperature of the electrolyte
(iii) nature of electrodes
(iv) area of electrodes.

For a freshly prepared cell, the value of internal resistance is generally low and goes on increasing as the cell is put to more and more use. The potential difference between the two electrodes of a cell in a closed circuit is called terminal potential difference and its value is always less than the emf of the cell in a closed circuit. It can be written as V = E – Jr.

(i) The terminal potential difference of two electrodes of a cell is equal to emf of the cell when

Answer: (b) I=0

(ii) A cell of emf E and internal resistance r gives a current of 0.5 A with an external resistance of 12Ω and a current of 0.25 A with an external resistance of 25Ω . What is the value of the internal resistance of the cell?

Answer:  (b) 1Ω

(iii) Choose the wrong statement.

Answer: (b) Internal resistance of a cell decrease with the decrease in temperature of the electrolyte.

(iv) An external resistance R is connected to a cell of internal resistance r, the maximum current flows in the external resistance, when

Answer: (a) R = r

(v) IF external resistance connected to a cell has been increased to 5 times, the potential difference across the terminals of the cell increases from 10 V to 30 V. Then, the emf of the cell is

Answer: (b) 60V

Question 2:

The potentiometer is an apparatus used for measuring the emf of a cell or potential difference between two points in an electrical circuit accurately. It is also used to determine the internal resistance of a primary cell. The potentiometer is based on the principle that, if V is the potential difference across any portion of the wire of length 1 and resistance R, then V∝l or V=klV∝l or V=kl where k is the potential gradient. Thus, the potential difference across any portion of the potentiometer wire is directly proportional to the length of the wire of that portion. The potentiometer wire must be uniform. The resistance of the potentiometer wire should be high.

(i) Which one of the following is true about the potentiometer?

Answer: (b) It measures the emf of a cell very accurately

(iii) Sensitivity of a potentiometer can be increased by

Answer: (a) decreasing potential gradient along the wire.

(iv) A potentiometer is an accurate and versatile device to make electrical measurements of EMF because the method involves

Answer: (b) a condition of no current flow through the galvanometer

(v) In a potentiometer experiment, the balancing length is 8 m, when the two cells Eand E2 are joined in series. When the two cells are connected in opposition the balancing length is 4 m. The ratio of the e. m. f. of two cells (El/E2) is

Answer: (d) 3: 1

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