An electrical power line, having a total resistance of $2 \, \Omega$, delivers $1 \, kW$ at $220 \, V$. The efficiency of the transmission line is approximately $....... \%$.

Two electric lamps of $40\, W$ each are connected in parallel. The power consumed by the combination will be ........... $W$.

Two electric bulbs have tungsten filaments of the same length. If one of them is rated $60\ W$ and the other $100\ W$,then:

If two electric bulbs have $40\, W$ and $60\, W$ rating at $220\, V$,then the ratio of their resistances will be

The ratio of heat dissipated per second through the resistance $5 \Omega$ and $10 \Omega$ in the circuit given below is:

Four wires of the same diameter are connected in turn between two points,maintained at a constant potential difference. Their resistivities and lengths are: $\rho$ and $L$ (wire $1$),$1.2\rho$ and $1.2L$ (wire $2$),$0.9\rho$ and $0.9L$ (wire $3$),and $\rho$ and $1.5L$ (wire $4$). Rank the wires according to the rates at which energy is dissipated as heat,greatest first.