question_answer

(a) Draw magnetic field lines of a bar magnet. "Two magnetic field lines never intersect each other." Why?

(b) An electric oven of 1.5 kW is operated in a domestic circuit (220 V) that has a current rating of 5 A. What result do you expect in this case?  Explain.

 

Answer:

(a) Two magnetic field lines do not intersect one another. The direction of magnetic field lines is always from north pole to south pole. If the two magnetic field lines do intersect. It means at the point of intersection the compass needle is showing two different directions which is not possible.

(b) Given:         Power, (P) = 1.5 kW \[=1.5~\times 1,000\] = 1,500 W

Voltage,             (V) = 220 V

We know,          \[P=V\times I\]

\[\Rightarrow \]               \[I=\frac{P}{V}=\frac{1,500}{220}=6.8A\]

Now, the current drawn by the oven is 6.8 A which is very high but the fuse in this circuit has   only 5A capacity. When a very high current of 6.8 A flows through 5A fuse, the fuse wire will get much. As a result the fuse wire will melt and the circuit thereby cutting off the power supply.