[填空题]
A cell with internal resistance r and emf ϵ is connected to a variable resistor R, an ideal ammeter and an ideal voltmeter.
1.State what is meant by terminal voltage.
2.Explain why the reading of the voltmeter is less than ϵ.
The variation of the reading of the voltmeter with the current I is shown in the graph.
3.Determine the emf ϵ and the internal resistance r of the cell.ϵ= ≪V≫
r= ≪Ω≫