An ideal transformer has a turns ratio of $10$. When the primary is connected to $220 \ V$,$50 \ Hz$ as a source,the power output is

$A$ transformer having efficiency $90 \%$ is working on $200 \ V$ and $3 \ kW$ power supply. If the current in the secondary coil is $6 \ A$, the voltage across the secondary coil and the current in the primary coil are respectively:

$A$ step-down transformer has $50$ turns on the secondary and $1000$ turns on the primary winding. If the transformer is connected to a $220 \ V, 1 \ A$ $A$.$C$. source,what is the output current of the transformer?

$A$ thermal power plant produces electric power of $600 \ kW$ at $4000 \ V$,which is to be transported to a place $20 \ km$ away from the power plant for consumers' usage. It can be transported either directly with a cable of large current carrying capacity or by using a combination of step-up and step-down transformers at the two ends. The drawback of the direct transmission is the large energy dissipation. In the method using transformers,the dissipation is much smaller. In this method,a step-up transformer is used at the plant side so that the current is reduced to a smaller value. At the consumers' end,a step-down transformer is used to supply power to the consumers at the specified lower voltage. It is reasonable to assume that the power cable is purely resistive and the transformers are ideal with a power factor unity. All the currents and voltages mentioned are rms values.
$1.$ If the direct transmission method with a cable of resistance $0.4 \ \Omega \ km^{-1}$ is used,the power dissipation (in %) during transmission is:
$(A) 20$ $(B) 30$ $(C) 40$ $(D) 50$
$2.$ In the method using the transformers,assume that the ratio of the number of turns in the primary to that in the secondary in the step-up transformer is $1:10$. If the power to the consumers has to be supplied at $200 \ V$,the ratio of the number of turns in the primary to that in the secondary in the step-down transformer is:
$(A) 200:1$ $(B) 150:1$ $(C) 100:1$ $(D) 50:1$
Give the answer for question $1$ and $2$.

An $80 \text{ W}$ lamp is connected to the secondary of a step-down transformer, where the primary is connected to an $AC$ mains of $220 \text{ V}$. Assuming the transformer to be ideal, the current in the primary winding is nearly: (in $\text{ A}$)

What is increased in a step-down transformer?