Physics Test - ...

A wire of irregular shape turning into a circular shape in a magnetic field which is directed into the paper. The direction of induced current is

Two circular coils can be arranged in any of the three situations shown in figure. Their mutual inductance will be,

A small square loop wire of side l is placed inside a large square loop of side L(L>>l). If the loops are coplanar and their centres coincide, the mutual induction of the system is directly proportional to

A step down transformer, transforms a supply line voltage of 2200 V into 220 V. The primary coil has 5000 turns. The efficiency and power transmitted by the transformer are 90 % and 8 kW respectively. Then the power supplied is

Which type of losses do not occur in the transformer?

The magnet in figure rotates as shown on a pivot through its centre. At the instant shown, what are the directions of the induced currents

Assertion: A spark occurs sometime, when an electric iron is switched off.

Reason: Sparking is due to large self-induced emf in the circuit during the circuit break

For the given circuit, calculate the current which is given by the battery:

(i) just after closing the key.

(ii) long time after closing the key.

The current i in an inductance coil varies with time t according to following graph,

Which one of the following graphs shows the variations of voltage in the coil?

A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately