The cathode of a photoelectric cell is changed such that the work function changes from $W_1$ to $W_2$ $(W_2 > W_1)$. If the current before and after the change are $I_1$ and $I_2$,respectively,and all other conditions remain unchanged,then (assuming $hv > W_2$):

When a body moves in a circular path,no work is done by the force since,

$\sim (p \vee q)$ is equal to

$A$ bullet of mass $0.02 \ kg$ travelling horizontally with velocity $250 \ ms^{-1}$ strikes a block of wood of mass $0.23 \ kg$ which rests on a rough horizontal surface. After the impact,the block and bullet move together and come to rest after travelling a distance of $40 \ m$. Find the coefficient of sliding friction of the rough surface. (Take $g = 9.8 \ ms^{-2}$)

In an unbiased $p-n$ junction,holes diffuse from the $p-$ region to $n-$ region because

$P-V$ plots for two gases during an adiabatic process are shown in the figure. Plots $1$ and $2$ should correspond respectively to