# When Deepak studies the electrical circuits and the current

## Case Study PhysicsChapter 3 – Current Electricity

When Deepak studies the electrical circuits and the current flowing through them, he became curious about the range of the currents we come across in daily life. He collected the data and presented in a tabular form as shown below. He then studied the instruments used to detect and measure current, however could not understand the difference between an ammeter and an ideal ammeter and thus went to this teacher for the explanation.

(i) What values did Deepak have ?                             (1)

(ii) As domestic appliances carry electric current of the order of few amperes, write one safety precaution we should take while working with them.                                                     (1)

(iii) An ammeter of resistance is connected in series with a resistor R and a battery of emf E and internal resistence r. The current flowing through this cicuit is . What will be the current flowing through the circuit, if the given ammeter is replaced by an ideal ammeter and find the percentage error in measuring the current through an ammeter ?                                 (2)                           [CBSE SQP 2017 – 18]

### Solution :

(i) Deepak has critical thinking and hard working value.

(ii) One should not touch the electrical appliances with wet hand.

(iii) The current through the circuit  is given by

When the given ammeter is replaced by an ideal ammeter, then

For ideal ammeter,

Percentage error in measurement of current through ammeter.

## Case Study Chapter 2Electrostatic Potential and Capacitance :

A capacitor is a system of two conductors separated by an insulator. The two conductors have equal and opposite charges with a potential difference between them. The capacitance of a capacitor depends on the geometrical configuration(shape, size and separation) of the system and also on the nature of the insulator separating the two conductors. They are used to store charges. Like resistors capacitors can be arranged in series or parallel or a combination of both to obtain desired value of capacitance.                                    [CBSE  2023]

Solution: See full solution