$A$ transformer consists of $500$ turns in the primary coil and $10$ turns in the secondary coil with a load of $10\, \Omega$. Find the current in the primary coil when the voltage across the secondary coil is $50\, V$. (in $A$)

Which of the following statements is correct regarding a step-down transformer?

The primary and secondary coils of a transformer have $50$ and $1500$ turns respectively. If the magnetic flux $\phi = \phi_0 + 4t$,where $\phi$ is in webers,$t$ is time in seconds and $\phi_0$ is a constant,the output voltage across the secondary coil is......$V$

$A$ transformer is used to light a $140\, W$, $24\, V$ lamp from a $240\, V$ $AC$ mains. The current in the main cable is $0.7\, A$. The efficiency of the transformer is......$\%$

$A$ distribution transformer with an efficiency of $90 \%$ supplies power to a colony of $10$ homes. All the $10$ homes have an electrical oven running at the same time,each drawing $20 \ A$ current from $220 \ V$ lines. The power dissipated as heat in the transformer is: (in $kW$)

The ratio of secondary to primary turns in a transformer is $3 : 2$. If the power output is $P$,then the input power,neglecting all losses,must be equal to: