A slab of material of dielectric constant $K$ has the same area as the plates of a parallel plate capacitor but has a thickness $(4/5)d$, where $d$ is the separation of the plates. The capacitance in the presence and absence of dielectric are $C$ and $C_0$ respectively. The ratio $(C/C_0)$ is

In a meter bridge experiment, the balance point is obtained at length '$l_1$' cm from left hand when resistances in the left gap and right gap are $15 \ \Omega$ and $R \ \Omega$ respectively. When the resistance $R$ is shunted with equal resistance the new balance point is at $(1.6\,l_1)$. The resistance $R$ in ohm is

In a potentiometer circuit when two cells of e.m.f. $1.5$ volt and $1.2$ volt are connected to assist each other, balancing length is $270$ cm. What will be the balancing length in cm when these two cells are connected in opposition?

The voltage across a lamp is $(6.0 \pm 0.3)$ volt and the current passing through it is $(4.0 \pm 0.1)$ ampere. The power consumed in watt will be (using percentage error)