The resistance of an ammeter is $13 \Omega$ and its scale is graduated for a current up to $100 \text{ A}$. After an additional shunt has been connected to this ammeter,it becomes possible to measure currents up to $750 \text{ A}$ by this meter. The value of the shunt resistance is

In tissue culture experiments,leaf mesophyll cells are put in a culture medium to form callus. This phenomenon may be called as:

$A$ galvanometer of resistance $50 \Omega$ is connected to a battery of $3 \text{ V}$ along with a resistance of $2950 \Omega$ in series. $A$ full-scale deflection of $30$ divisions is obtained in the galvanometer. In order to reduce this deflection to $20$ divisions,the total resistance in series should be: (in $\Omega$)

$A$ constant voltage of $25 ~V$ is applied to a series $L-R$ circuit at $t=0$,by closing a switch. What is the potential difference across the resistor and the inductor at time $t=0$?

Sunlight of intensity $1.3 ~kW ~m^{-2}$ is incident normally on a thin convex lens of focal length $20 ~cm$. Ignore the energy loss of light due to the lens and assume that the lens aperture size is much smaller than its focal length. The average intensity of light,in $kW m^{-2}$,at a distance $22 ~cm$ from the lens on the other side is.

The imperfect fungi which are decomposers of litter and help in mineral cycling belong to