What is the function of a key (or switch) in an electric circuit ?
What is a circuit diagram? Draw the labeled diagram of an electric circuit comprising of a cell, a resistor, an ammeter, a voltmeter and a closed switch (or closed plug key). Which of the two has a large resistance: an ammeter or a voltmeter?
Answer the following questions.
(a) Why is the direction of the current in an electric motor reversed after every half round?
(b) How can the strength of an electro-magnet be increased?
(c) What is the principle of the electric motor?
(d) Why is there a key in an electrical circuit?
(e) Is the mechanism of a shirt button like that of the key in an electric circuit?