(1) according to the ohm's law of closed circuit, there are E=IR+Ir, R=E? 1I-r, obtained by mathematical knowledge, in which the vertical axis intercept represents the internal resistance of the battery, the slope represents the electromotive force, and there are

The electromotive force of the battery E=△R△( 1I)=90000? 50000( 19.9? 15.8)× 103V=0.96V, and the internal resistance r =10.5x103ω =10.05x0/04ω.

(2) The actual battery internal resistance is small, such as dry battery and lead battery less than 1 ohm, and the internal resistance of fruit battery power supply is too large, so it has no practical use value.

So the answer is:

(1)0.96 volt, 1.05× 104ω.

(2) The internal resistance of power supply is too large